Arsenal ended their away hoodoo against Premier League title challengers with a 2-0 victory at Manchester City on Sunday that left Chelsea five points clear at the top.
Santi Cazorla gave Arsenal the lead from the penalty spot in the 24th minute, after returning City skipper Vincent Kompany felled Nacho Monreal, and Olivier Giroud doubled the lead in the 67th minute with a deft header from Cazorla's free kick.
City included fit-again Sergio Aguero in their starting lineup for the first time since early December but the Argentine was largely anonymous against a vastly-improved Arsenal defence.
The result lifted Arsenal to fifth on 39 points and one behind Manchester United in fourth.
The end of second-placed City's 12-match unbeaten run left them on 47 points to Chelsea's 52 with their next league outing a daunting trip to Stamford Bridge on Jan. 31.
European hopefuls West Ham United earlier revived their push for a top-four finish with a 3-0 victory over relegation-threatened Hull City at Upton Park.
The result sent the Hammers up to seventh with 36 points from 22 games, just four behind Manchester United. Struggling Hull are 18th, level with Queens Park Rangers and two points above bottom-of-the-table Leicester City.
‘Cazorla was different class’
Arsenal were a far tougher nut to crack to the one that lost 6-3 at City last season and Cazorla epitomised a team performance full of hard work and endeavour.
"It's not an easy place to come, and Manchester City have made this a bit of a fortress, but we've done well and got the win. Santi Cazorla was different class," Arsenal midfielder Aaron Ramsey told Sky Sports.
Arsenal were compact, disciplined and resolute as City dominated possession in the opening exchanges.
In the 22nd minute Monreal was blocked by Kompany as he raced onto a one-two with Giroud and referee Mike Dean pointed to the spot. Cazorla nervelessly dispatched the penalty past a despairing Joe Hart. The ease with which Arsenal dealt with City's attacking raid's prompted the introduction of Stevan Jovetic at halftime.
Giroud doubled the lead
With his arrival City reverted to 4-4-2 and twice went close after the resumption when Aguero curled an effort wide before Jesus Navas' rasping shot was parried by David Ospina.
Navas' teasing cross was then diverted for a corner as City players queued up at the back post.
Just when City's pressure threatened to reach breaking point Arsenal doubled their lead through Giroud who met Cazorla's accurate free kick with a delicate header. City laid siege to the visitors' goal but Arsenal held firm for their first win away at either of the two Manchester clubs since 2010 when they beat City 3-0.
Happy Hammers
With Sone Aluko leading Hull's attack in the absence of a host of first-choice forwards including Nikica Jelavic, the visitors were the better team in the first half at Upton Park but were hindered by poor decision making at crucial times.
Hull's already injury-ravaged squad received another blow when defender James Chester was helped off with a dislocated shoulder.
The second half saw West Ham reassert themselves, with Enner Valencia's speculative shot parried by goalkeeper Allan McGregor and in-form Andy Carroll bundling home the loose ball.
Substitute Morgan Amalfitano then doubled the lead with a delightful chip after 69 minutes.
Three minutes later Alex Song split Hull's defence with a fantastic pass and the reinvigorated Stuart Downing, one-on-one with McGregor, applied a routine finish.
