Manchester - Santi Cazorla scored one goal and made another as Arsenal damaged Manchester City's Premier League title challenge with a brilliant 2-0 victory at a chilly Etihad Stadium on Sunday.
The Spanish midfield scored a 24th-minute penalty and teed up Olivier Giroud for a second-half header to re-energise Arsene Wenger's side's push for a top-four finish, and maybe more.
Victory avenged Arsenal's crushing 6-3 loss on their last visit to this ground in December 2013 and left Manuel Pellegrini's City five points adrift of leaders Chelsea, who they play at Stamford Bridge on January 31.
For Arsenal, wins against major rivals have been few and far between in recent years, but having closed to within a point of fourth-place Manchester United, and 13 points of Chelsea, they will approach the run-in with renewed ambition.
It was City's first defeat in 15 games and gave Arsenal a first win at the Etihad since a 3-0 success in October 2010, which was the last time the home side had lost by a two-goal margin on their own turf in the league.
City have now conceded two or more goals in three successive home league games for the first time since October 2002, which will deeply concern Pellegrini ahead of their trip to Chelsea in two weeks' time.
Vincent Kompany and Sergio Aguero both made their first City starts since December after injury, but though much had been made of the anticipated showdown between Aguero and Alexis Sanchez, it was Kompany who unwittingly took centre-stage.
City were quick to force Arsenal back, with Laurent Koscielny booked for felling Fernandinho, but with five players strung across midfield, the visitors were content to soak up pressure and attack on the break.
Sanchez gave City a warning with a dart to the edge of the box, before an alert intervention from Kompany prevented Giroud from testing Joe Hart with a near-post header.
It was authoritative defending by the City captain, but mid-way through the first half he handed Arsenal the chance to go ahead.
When Nacho Monreal knocked the ball past him, Kompany stepped across the Spaniard's path and despite raising his hands in a show of innocence, there was contact, and Monreal went down.- Giroud steals in -
Referee Mike Dean pointed to the spot and Cazorla coolly placed a shot inside Hart's left-hand post to claim his sixth goal of the campaign.
With City's fans indignant, the home side began to apply pressure, but a meek header from Aguero that drifted harmlessly wide was the best they mustered before half-time.
Pellegrini showed his intent by introducing forward Stevan Jovetic in place of midfielder James Milner at the break and his side flew out of the traps.
Aguero and Fernandinho both had shots deflected behind, while Jesus Navas warmed David Ospina's palms with a rising drive.
It took a timely touch from Koscielny to prevent either Aguero or Jovetic from polishing off a cross from Navas, but Arsenal remained a threat on the break, with Aaron Ramsey shooting over.
Frank Lampard entered the fray for City in the 63rd minute, but he had been on the pitch for only three minutes when Arsenal added a second.
After Sanchez won a central free-kick, Cazorla flighted a cross into the box and Giroud stole in behind Fernando to nod a close-range header past a flat-footed Hart for his seventh goal this season.
Sanchez could have made it 3-0, cutting in from the left and working Hart with a curling shot.
City missed the impetus of Yaya Toure, on international duty with Ivory Coast, and the injured Samir Nasri, and their attempts at the other end lacked precision.
Ospina saved comfortably from Navas and substitute Edin Dzeko, while Arsenal's biggest scare came when Monreal sliced an attempted clearance over his own bar.