Chelsea’s Morgan Rogers opened the scoring in the 50th minute at Stamford Bridge, and a rash challenge from Lisandro Martinez then saw Man Utd, who had captain Bruno Fernandes back in the fold, sent off for a second yellow card.
Palmer made it 2-0 from the penalty spot in the 64th minute, getting Chelsea back on track after their Premier League loss to Tottenham Hotspur and their midweek EFL Cup exit at the hands of Liverpool.
Man Utd’s defeat leaves them winless in nine games in all competitions – their worst run since 1988.
How the match unfolded
Chelsea winger Estevao had an early goal disallowed, but Fernandes should have put Man Utd ahead when he connected with Bryan Mbeumo’s low cross, only to blaze over.
Matheus Cunha thought he had given Man Utd the lead when he scored from Harry Maguire’s header, but the goal was disallowed for offside after a VAR review.
Amad then let Chelsea defender Wesley Fofana off the hook when he fired over after an error from the centre-back, while Pedro Neto drilled wide at the other end following Maguire’s mistake.
Chelsea took the lead five minutes into the second half, with Rogers charging through a gaping midfield and defence before lifting a delicate finish over goalkeeper Senne Lammens.
And it got worse for Man Utd in the 63rd minute when Martinez, who had just been booked for dragging back Rogers, lunged in forearm first on Fofana when defending a set-piece.
Referee Peter Bankes did not award the foul initially, but VAR recommended an on-field review, after which the official pointed to the penalty spot and gave Martinez his marching orders. Palmer converted the spot-kick, although Lammens will likely be disappointed he did not keep it out.
Estevao scored in the 71st minute, only to be denied by a VAR review for offside.
Mbeumo rattled the crossbar in stoppage time, but Chelsea kept their sheet clean as they moved into fourth place, while Man Utd sit 16th.
