Arsenal avenged their trhashing at the hands of Manchester City at the Etihad Stadium on Sunday with a 2-0 victory that stunned the blues. The defeat leaves City five points behind leaders Chelsea who City play in a now must win game at the end of the month. City included Sergio Aguero in the starting lineup, after a month-long injury absence.
As the first half started 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.
The Gunners then took the lead on 24 minutes after City skipper Vincent Kompany, blocked Nacho Monreal in the area. Santi Cazorla shouldered the responsibility of taking the spot-kick, and the Spaniard made no mistake, slotting the ball past the despairing dive of Joe Hart.
City looked sharper afeter the break when Pellegrini introduced Jovetic on for Milner.
Aguero and Fernandinho both had shots deflected behind, while Jesus Navas warmed David Ospina's palms with a rising drive.
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.