A rejuvenated Arsenal recorded an important victory over Chelsea to end their seven-game run without a win in the Premier League and ease the pressure on boss Mikel Arteta.
Two first-half goals set the platform for the Gunners' first top-flight win since 1 November.
Alexandre Lacazette sent goalkeeper Edouard Mendy the wrong way from the penalty spot and Granit Xhaka curled in a superb free-kick 10 minutes later to put Arteta's side in control.
Bukayo Saka's cross then dropped into the top corner early in the second half to put the game beyond the visitors.
Tammy Abraham scored from close range to make it a nervy final five minutes for the hosts and Jorginho then saw his weak penalty saved by Bernd Leno.