Kai Havertz scored twice against his former club as Arsenal tightened their grip on top spot in the Premier League by denting Chelsea's European aspirations with a thumping 5-0 win.
Gunners forward Havertz, who made a £65million switch from Stamford Bridge last summer, registered two of four second-half goals on a remarkable evening at a jubilant Emirates Stadium.
Defender Ben White also claimed a brace for Mikel Arteta's title-chasing side, adding to Leandro Trossard's early opener, as the Blues' recent resurgence floundered in embarrassing fashion in the absence of key man Cole Palmer.