Manchester United suffered their third consecutive defeat as Chelsea capitalised on their second-half collapse, increasing pressure on manager Michael Carrick.
United have now gone nine matches without a win in all competitions, their longest such run since 1988. Their fourth Premier League defeat leaves them 16th, just one point above the relegation zone.
“We seemed to be in a good position, but somehow turned everything upside down in the second half,” Carrick said after the match.
Morgan Rogers put Chelsea ahead shortly after the break. United's situation worsened when Lisandro Martinez was sent off for elbowing Wesley Fofana inside the box.
Cole Palmer converted the resulting penalty to seal Chelsea's victory.
Carrick said he had not yet reviewed Martinez's red-card incident but denied being disappointed with the defender.
Chelsea moved up to fourth with 16 points from nine matches, while United ended the week in further disappointment.
-AJM