Samuel Eto'o seized on slack defending to score his first Chelsea hattrick in a 3-1 victory over Manchester United that provided further evidence of the Premier League champions' struggles under David Moyes.
It was United's seventh league loss, leaving them not only 14 points behind leader Arsenal but six points from the fourth Champions League spot.
Eto'o put Chelsea in front in the 17th minute with a deflected shot, tapped in another on the stroke of halftime, and scrambled in the third in the 49th.
By the time Javier Hernandez pulled one back from close range in the 78th, a 100th Premier League win for Jose Mourinho already looked secure.
And United now faces three matches without captain Nemanja Vidic, who was sent off in stoppage time.