Arsenal felt the full force of Manchester City's rampant attack to slump to a 6-3 loss in the Premier League on Saturday, cutting its lead to two points and throwing the title race wide open.
Chelsea pounced on Arsenal's implosion at Etihad Stadium by edging past Crystal Palace 2-1 at home, with Ramires scoring the winner to lift Jose Mourinho's team provisionally into second place.
But approaching the halfway stage of the campaign, City is likely to be most people's favourite for the title after following up big home wins over Manchester United and Tottenham already this season with another masterful attacking display against Arsenal.
What had been the tightest defence in the league was ripped apart, with City's eighth straight home win sealed by goals from Fernandinho (two), Sergio Aguero, Alvaro Negredo, David Silva and Yaya Toure.
City enhanced its tag as the Premier League's entertainers — it has scored 35 goals in eight home matches, including six past Spurs and four past United — and is a point adrift of Chelsea in third.
"It was a very complete game in attacking," City manager Manuel Pellegrini said. "It is not easy to score six goals against Arsenal, the best defence in the Premier League."
Everton wins, Newcastle held to draw
Everton brushed past Fulham 4-1 with three late goals to jump to fourth, Newcastle drew 1-1 with Southampton in a match that ended in a scuffle between the two benches and Cardiff beat West Bromwich Albion 1-0.
Sunderland is four points adrift in last place after a 0-0 draw at West Ham.
Arguably the standout match in this season's Premier League lived up to its billing, with weary Arsenal run ragged by City less than three days after the Gunners' grueling defeat in the Champions League at Napoli.
Arsenal's title credentials were always going to be tested in this crucial three-game period, starting with last weekend's 1-1 draw at Everton and ending with a home match at Chelsea on Dec. 23, and cracks have been found.
"We made too many mistakes," Arsenal manager Arsene Wenger said. "Our strength until now was our defensive discipline but that went as the game went on."
The prolific strike pairing of Aguero and Negredo put City 2-1 up at halftime, with Theo Walcott's goal having made it 1-1.
Fernandinho scored in the 50th, moments after Aguero went off with a calf injury only for Walcott to score again, but Arsenal's creaking defence was breached in the final 24 minutes by Silva, Fernandinho and Toure's penalty. Per Mertesacker netted Arsenal's other goal in injury time.
Arsenal midfielder Jack Wilshere could face disciplinary action after being pictured raising his middle finger toward City's fans during the second half.
With Liverpool not playing until Sunday, Chelsea is now Arsenal's closest challenger after an unconvincing win over Palace at Stamford Bridge.
Fernando Torres scored in the 16th minute for the Blues before Joel Ward set up Marouane Chamakh to equalize for the visitors in the 29th. Six minutes later, Ramires grabbed the winner with a right-footed shot from outside the area to the top left corner.
Everton maintained its challenge for a top-four finish by scoring three goals in the final 17 minutes to see off Fulham.
Leon Osman's 18th-minute goal on his 300th Premier League game put Everton ahead but Dimitar Berbatov equalized from the penalty spot in the 67th.
Seamus Coleman regained the home side's lead before Gareth Barry and Kevin Mirallas completed victory.
Jay Rodriguez earned Southampton a point at Newcastle after cancelling out Yoan Gouffran's first-half strike, but the match ended with ugly scenes on the sidelines with people on both benches clashing in reaction to a foul on the pitch.
A member of each coaching staff was sent off.
"It was bit of panto season at the end," said Newcastle manager Alan Pardew, playing down the incident.
Peter Whittingham scored the second-half winner for Cardiff against West Brom, lifting the Welsh team four points clear of the bottom three and inflicted a fourth straight defeat on the visitors.
Hull hosts Stoke in the late game.
On Sunday, it's: Tottenham vs. Liverpool and Aston Villa vs. Man United.