Ruud van Nistelrooy (left) and Real Madrid are the team to beat in this year's Champions League. (Jasper Juinen/Getty Images)

The list of previous champions is long, and it includes such historic soccer clubs as Real Madrid, Liverpool, AC Milan, Bayern Munich, Ajax Amsterdam and Benfica.

Ever since 1955, the biggest and best teams in the world have won European soccer's annual Champions League, the most important club tournament in the sport.

Dwarfed only by the World Cup and Euro in importance and prestige, the Champions League and its forerunner, the European Cup, have drawn the champions and the very best teams from across Europe into a single winner-take-all super tournament for more than 50 years.

Talk about a smorgasbord of soccer!

Last year, Brazilian superstar Kaka led AC Milan to victory over Liverpool in the final in Athens in a rematch of the 2005 final.

The 2007-08 tournament kicks off on Tuesday with several pressing questions on the minds of soccer fans around the world:

Can AC Milan repeat as champions? Can Spanish giants Real Madrid win their 10th European title? Can London super-club Chelsea finally break through and win it all?

CBCSports.ca tries to offer some answers with this comprehensive breakdown of the teams and players to watch on the road to the final next May in Moscow.

THE FAVOURITES

Real Madrid (Spain)
2006-07 result: Second round
Best result: Champions (1956, 1957, 1958, 1959, 1960, 1966, 1998, 2000 and 2002)
After winning their first Spanish league title in four seasons last year, Real Madrid now focus their attention on winning their first Champions League crown since 2002. The Spanish champions bid farewell to the last of the Galacticos - David Beckham and Roberto Carlos - and invested hundreds of millions of dollars in new players, including Dutch trio Wesley Sneijder, Royston Drenthe and Arjen Robben, and defenders Gabriel Heinze (Argentina), Pepe (Portugal) and Christoph Metzelder (Germany). New coach Bernd Schuster is already under pressure from club management to deliver a 10th Champions League title for Los Blancos. Anything short of that will be considered a failure, especially after Madrid meekly bowed in the second round the last two years. Look for Sneijder and Robben to drive the attack for the Spaniards in midfield, while the always dangerous Ruud van Nistelrooy, one of the most lethal forwards in the game, will provide the goals.
Typical starting lineup: (GK) Casillas - (D) Ramos, Cannavaro, Pepe, Drenthe - (M) Diarra, Robben, Sneijder, Robinho - (F) Raul, Van Nistelrooy
Key player: Ruud van Nistelrooy

Manchester United (England)
2006-07 result: Semifinals
Best result: Champions (1968 and 1999)
Like Real Madrid, Manchester United heavily invested in new players during the off-season, signing Argentine forward Carlos Tevez, and Portuguese midfielders Nani and Anderson. The most notable newcomer, though, is Calgary-born midfielder Owen Hargreaves. The Red Devils were long-time admirers of the former Bayern Munich star, but after they were bullied around by Genaro Gattuso and AC Milan in last year's semifinals, manager Sir Alex Ferguson made it a priority to go after Hargreaves in order to toughen up the midfield. Hargreaves will take care of the dirty work, allowing fellow midfielders Ryan Giggs, Paul Scholes and Cristiano Ronaldo to lead the attack. Ronaldo disappointed in last year's tournament, so look for him to have a breakout campaign. Tevez is a world-class player, and should combine brilliantly with Wayne Rooney up front. Rio Ferdinand and Nemanja Vidic form a deadly duo in the centre of the defence, although they are prone to lack concentration from time to time.
Typical starting lineup: (GK) Van der Sar - (D) Neville, Ferdinand, Vidic, Evra - (M) Hargreaves, Giggs, Ronaldo, Scholes - (F) Rooney, Tevez
Key player: Cristiano Ronaldo

Inter Milan (Italy)
2006-07 result: Second round
Best result: Champions (1964 and 1965)
If there's one team with a point to prove in this year's tournament, it's Inter. Buoyed by the class of Serbian playmaker Dejan Stankovic and Swedish striker Zlatan Ibrahimovic, the Nerazzurri romped to the Serie A title last season but disappointingly bowed out of the Champions League in the second round. Crosstown rivals AC Milan, meanwhile, claimed a seventh European title, stealing the headlines from Inter. The Italian league champions look set to make a solid run at winning this tournament for the first time since 1965. Coach Roberto Mancini has the nucleus of last year's side intact, and added a few key players, including Honduran forward David Suazo, Romanian defender Cristian Chivu, and Chilean midfielder Luis Jiminez. Inter have plenty of depth at every position - Argentina forward Hernan Crespo could struggle to see action with the arrival of Suazo - and are well-organized defensively. Ibrahimovic will be his mercurial best, scoring highlight-reel goals for the Italians.
Typical starting lineup: (GK) Cesar - (D) Maxwell, Materazzi, Chivu, Maicon - (M) Viera, Dacourt, Stankovic, Zanetti - (F) Ibrahimovic, Suazo
Key player: Zlatan Ibrahimovic

Chelsea (England)
2006-07 result: Semifinals
Best result: Semifinals (2004, 2005 and 2007)
Like Inter, Chelsea has a point to prove. The London club has been knocking on the door (it lost in the semifinals three of the last four years), but manager Jose Mourinho's team could be ready to finally walk through it. Ivory Coast forward Didier Drogba is coming off a great season in the Premiership, winger Shaun Wright-Phillips has finally come into his own, and John Terry and Ricardo Carvalho form one of the best central defensive pairings in the European game. The addition of Florent Malouda will give the Chelsea attack more width, as the Frenchman will take the place of departed winger Arjen Robben (now with Real Madrid). There are some concerns, though. Terry's prolonged absence last season due to injury exposed Chelsea's lack of depth at the back. Brazilian Alex was signed in the off-season, but the Blues are still lacking another top-quality defender. Also, German playmaker Michael Ballack and Ukrainian forward Andriy Shevchenko seem to be at odds with Mourinho over their lack of playing time and that could pose a major distraction for the team.
Typical starting lineup: (GK) Cech - (D) Belletti, Terry, Carvalho, Cole - (M) Wright-Phillips, Lampard, Essien, Obi-Mikel, Malouda - (F) Drogba, Shevchenko
Key player: Didier Drogba

ON THE RISE

Mario Gomez leads the attack for Stuttgart. (Torsten Silz/AFP/Getty Images)

VfB Stuttgart (Germany)
2006-07 result: did not qualify
Best result: Second round (2004)
Stuttgart stunned critics in Germany when it came from nowhere to win last season's Bundesliga crown, its first since 1992. This is a fairly young side, but the team plays with a maturity far beyond its average age of 25. Stuttgart is greater than the sum of its parts, combining guile, hard work and determination in midfield. Serdar Tasci is a versatile midfielder who perfectly compliments goal-scoring midfielder Sami Khedira, creative spark plug Robert Hilbert and Thomas Hitzlsperger. Up front, striker Mario Gomez gives Stuttgart a legitimate scoring threat, while Portugal's Fernando Meira and Frenchman Mathieu Delpierre anchor the defence with their athleticism and intelligence. The addition of Romanian youngster Ciprian Marica, purchased from Ukrainian team Shakhtar Donetsk, should help take the pressure off of Gomez. The key signing, though, was goalkeeper Rafael Schafer, who replaces Timo Hildebrand, now with Valencia after six seasons with Stuttgart.
Typical starting lineup: (GK) Schafer - (D) Meira, Osorio, Boka, Tasci - (M) Pardo, Hitzlsperger, Hilbert, Khedira - (F) Gomez, Marica
Key player: Mario Gomez

FC Barcelona (Spain)
2006-07 result: Second round
Best result: Champions (1992 and 2006)
The Catalan club walked away empty-handed last season after failing to defend its Spanish league and Champions League title - Barcelona finished second to Real Madrid in La Liga and bowed out in the second round of the Champions League. That was enough for Dutch manager Frank Rijkaard to make some moves in the transfer market. Frenchman Eric Abidal and Gabi Milito of Argentina reinforce a top-notch defence that already includes Carlos Puyol, Gianluca Zambrotta and Lillian Thuram. Yaya Toure of the Ivory Coast gives the Catalans more grit in midfield. The big signing, though, was French striker Thierry Henry. The former Arsenal star comes to Spain with a glittering reputation and should pair up brilliantly with fellow striker Samuel Eto'o. The Spaniards are not too shabby when it comes to attacking options in midfield, either. Lionel Messi, Ronaldinho and Deco are all explosive playmakers who can score and give the Barcelona attack its cutting edge.
Typical starting lineup: (GK) Valdes - (D) Abidal, Puyol, Milito, Zambrotta - (M) Deco, Xavi, Ronaldinho, Messi - (F) Henry, Eto'o
Key player: Thierry Henry

ON A SLIDE

AC Milan (Italy)
2006-07 result: Champions
Best result: Champions (1963, 1969, 1989, 1990, 1994, 2003 and 2007)
The reigning champions failed to make a splash in the transfer market - the Rossoneri limited themselves to buying defensive midfielder Emerson and Brazilian forward Alexandre Pato who, because of age restrictions, won't be eligible to play until he turns 18 in January. Why Milan didn't see the need to bolster its aging defence (captain Paolo Maldini is 39) is anybody's guess, but the decision not to bring in another two or three young defenders will hurt the team. Goal-scoring could also be a problem. Filippo Inzaghi is 34 and has lost a step of pace, Ronaldo is battling injuries, and Alberto Gilardino has completely lost his scoring touch. With that in mind, even more pressure will be place on Brazilian Kaka, last season's Champions League MVP, to lead the attack. Heaven forbid he gets injured, because without him, the Italians will stutter. With the defence not getting any younger, Brazilian goalkeeper Dida, prone to making big mistakes in big games, will be badly exposed.
Typical starting lineup: (GK) Dida - (D) Maldini, Nesta, Oddo, Kaladze - (M) Gattuso, Emerson, Pirlo, Seedorf - (F) Kaka, Ronaldo
Key Player: Kaka

Olympique Lyon (France)
2006-07 result: Second round
Best result: Quarter-finals (2004, 2005 and 2006)
After winning a sixth straight French league title, Olympique Lyon is anxious to prove it belongs on European soccer's biggest stage. Although possessing plenty of skilled players, the knock on Lyon was that they lacked the tactical nous to advance to the final four - Lyon crashed out in the second round last year, after reaching the quarter-finals the three previous years. Massive changes at the club mean Lyon will have to wait at least another year to reach the semifinals. Coach Gerard Houlier is gone, as are several key players: Florent Malouda (now with Chelsea), defender Eric Abidal (FC Barcelona), and midfielders Alou Diarra (Bordeaux) and Tiago (Juventus). The only major addition to the club was defender Fabio Grosso, and the Italian has looked shaky in French league games for Lyon thus far. First-team goalkeeper Gregory Coupet and Brazilian central defender Cris will miss several months of action due to injuries. Playmaker Juninho is at odds with Sidney Govu over comments the Frenchman made about the Brazilian, which could hurt the team's chemistry on the field.
Typical starting lineup: (GK) Vercoutre - (D) Reveillere, Squillaci, Grosso, Bodmer - (M) Toulalan, Kallstrom, Govou, Juninho - (F) Keita, Benzema
Key player: Juninho

THE DARK HORSES

Francesco Totti is the heart and soul of AS Roma. (Andreas Solaro/AFP/Getty Images)

AS Roma (Italy)
2006-07 result: Quarter-finals
Best result: Finalist (1984)
Roma is still smarting from its 7-1 loss to Manchester United at Old Trafford in the quarter-finals last season, but the Giallorossi are a strong team and manager Luciano Spalletti is a formidable tactician who doesn't tie himself down to one formation. Francesco Totti, last year's winner of the Golden Shoe award as Europe's top scorer, is playing his best soccer in years and, supported by the likes of Mancini and Rodrigo Taddei, he leads a dangerous and potent Roma attack. The defence is pretty solid, even with the departure of Cristian Chivu to Inter Milan - Roma drafted in Brazilian Juan as his replacement. Youngsters Daniele De Rossi and Roberto Aquilani give the Italians a creative force in midfield, while Simone Perrotta acts as the policeman in the centre of the park. French winger Ludovic Giuly was an excellent addition, giving Roma more attacking options on the wing. It'll be interesting to see how Roma balance the demands of the Champions League and the Serie A season, but they have enough depth to cope.
Typical starting lineup: (GK) Doni - (D) Pannuci, Juan, Mexes, Tonetto - (M) De Rossi, Perrotta, Mancini, Taddei - (F) Giuly, Totti
Key player: Francesco Totti

Sevilla (Spain)
2006-07 result: Did not qualify
Best result: Never qualified for the Champions League before.
After winning the UEFA Cup the last two seasons, Sevilla is now ready to play with the big boys. The Spanish outfit is an exciting, talented and attack-minded team that plays an entertaining brand of soccer. Even though they'll be making their Champions League debut, the Spaniards have plenty of experience. Juande Ramos is one of the most tactically astute managers in European soccer and gets the most out of his players. After years of underachieving in England, Mali forward Fredi Kanoute has developed into one of the game's most prolific strikers in Spain. Brazilian wingback Daniel Alves anchors a strong defence and gives Sevilla another attacking option with his probing runs down the wings. Danish playmaker Christian Poulsen and Italian Enzo Maresca has never received the accolades they deserve, but they are both skilful midfielders who can dictate the pace of game. Goalkeeper Andres Palop is an unheralded shot-stopper, capable of winning games on his own. The tragic passing of star midfielder Antonio Puerta, 22, means Sevilla has even more incentive to succeed.
Typical starting lineup: (GK) Palop - (D) Hinkle, Dragutinovic, Escude, Alves - (M) Navas, Poulsen, Maresca, Adriano - (F) Fabiano, Kanoute
Key player: Fredi Kanoute