In-form striker Robin van Persie scored a hat-trick as Arsenal edged Chelsea in a stunning derby.Chelsea's Frank Lampard opened the scoring with a stooping header but Van Persie levelled into an empty net.John Terry re-established Chelsea's lead from 16 yards before Andre Santos equalised from the egde of the box.Gunners' Theo Walcott scored after a run and Chelsea's Juan Mata fired home a stunner before Van Persie tapped into an empty net then smashed home another.Van Persie's last two goals came in the last five minutes, with the first of those two coming when Terry slipped from Florent Malouda's poor back-pass, leaving the Dutchman in miles of space to sidestep Petr Cech and slot home.And then the striker was played in by Mikel Arteta in injury-time and Cech could not keep his shot out.The win lifts Arsenal up to sixth in the table.