Argentina, Spain advance in Davis Cup

Novak Djokovic tried to help Serbia stage a comeback in their semifinal against Argentina despite a lingering back problem, but had to retire when trailing 7-6 (5), 3-0 against Juan Martin del Potro. That sent Argentina into the final against Spain.

Novak Djokovic's ailing back didn't hold up Sunday, meaning Rafael Nadal won't have to face his main nemesis in this year's Davis Cup final.

Djokovic tried to help Serbia stage a comeback in their semifinal against Argentina despite a lingering back problem, but had to retire when trailing 7-6 (5), 3-0 against Juan Martin del Potro. That sent Argentina into the final against Spain, which advanced after Nadal routed Jo-Wilfried Tsonga 6-0, 6-2, 6-4 on clay in Cordoba.

"I feel disappointed to end this tie this way," Djokovic said. "My condition was 60 per cent of what I had expected."

Argentina ended up winning 3-2 after Serbia's Janko Tipsarevic took the final meaningless match when Juan Monaco retired after losing the first set 6-2. Spain completed a 4-1 win after Fernando Verdasco beat Richard Gasquet in the final match.

Djokovic didn't play at all on Friday, pulling out of the opening singles because his back had not recovered sufficiently from the injury he sustained during Monday's U.S. Open final victory over Nadal.

But with Serbia trailing 2-1 going into the final day, the top-ranked Serb decided to give it a try. It didn't work out, however, as he fell to the floor with back pains while trying to return a forehand during the final point of the third game in the second set, and couldn't continue after that.

"I'm sad for him and wish him fast recovery," Del Potro said. "He has everything to keep the No. 1 position."

It seems injuries are about the only thing that can stop Djokovic this year. He entered the weekend with a 64-2 record this year, having won three majors. One of those two losses came when he had to retire with a sore shoulder against Andy Murray in the Cincinnati final last month.

The only player to beat Djokovic when fit this year is Roger Federer, in the French Open semifinals. Nadal certainly hasn't been able to, losing all six of his matches against the Serb in 2011 — all of them in finals. The Spaniard was unusually blunt when he said this week he'd rather face Argentina than Serbia in the final.

Nadal also complained of fatigue after the gruelling U.S. Open final, but unlike Djokovic he showed no symptoms of it this weekend.

After a similarly impressive victory against Richard Gasquet on Friday, Nadal dominated the 10th-ranked Tsonga at Cordoba's bullring to give the hosts a chance at a third title in four years. Playing in temperatures hovering above 30 degrees Celsius all weekend, Nadal dropped just 10 games in two matches.

Clay-court dominance

"Simply put, Rafa was just too good this weekend," Tsonga said. "He's the best player ever on clay court, I think, he's practically unbeatable on this surface and today we didn't create the exception."

Nadal is now 14-0 on clay in Davis Cup and 18-1 overall, his only loss coming on his debut. Nadal has already won three Davis Cup titles and will lead Spain into its sixth final since 2000 and eighth overall.

"You might think it gets easier to win but it doesn't," Nadal said. "Thanks to the excellent relations inside the team, the Spanish players have stayed united over the years to keep winning."

In the World Group playoffs, Russia, Croatia, Austria and Japan all secured spots in next year's elite competition.

Russia rallied from 2-1 down against Brazil after Mikhail Youzhny defeated Thomaz Bellucci 2-6, 6-3, 5-7, 6-4, 14-12 in a five-hour marathon in the first reverse singles. Dmitry Tursunov then won the deciding match over Ricardo Mello 6-1, 7-6 (5), 2-6, 6-3.

Youzhny failed to serve out the match at 5-4 in the fifth, and then had to save two match points in the 18th game. At 12-all, Youzhny converted his second break point when the Brazilian netted a forehand, and the Russian served out the match at love.

Roger Federer's Switzerland clinched its spot in the World Group after Stanislas Wawrinka needed only four minutes Monday to complete a 4-6, 6-4, 6-7 (7), 6-4, 6-3 win over Australia's Lleyton Hewitt.

Wawrinka led 5-3 in the fifth set Sunday when darkness suspended the 3-hour 58-minute match. On Monday, on a grass court at Royal Sydney Golf Club, Wawrinka broke Hewitt's serve and the official match time became 4:02.

On Sunday, Roger Federer defeated Bernard Tomic 6-2, 7-5, 3-6, 6-3 to pull Switzerland level at 2-2 after Australia won Saturday's doubles and the teams split the opening singles on Friday.

Australia, which has won the Davis Cup 23 times, second only to the United States' 32 titles, will spend a fifth year out of the top competition.