Romelu Lukaku scored twice as Manchester United maintained their unbeaten start run in the Premier League under Ole Gunnar Solskjaer.
Lukaku struck either side of half-time as United took control of the contest at Selhurst Park but a fine header from Joel Ward jolted the home crowd into life.
But as Palace pushed for an equaliser United pounced in the counter with Paul Pogba threading a ball through for Ashley Young to wrap up the win.
Without a clutch of first-team players, including Nemanja Matic, Ander Herrera, Jesse Lingard, Juan Mata and Anthony Martial, Lukaku took his chance back in the first-team, brilliantly finding the far corner with a precise finish after 33 minutes.
The Belgium international doubled his tally seven minutes into the second half, hooking a fine effort past Vicente Guaita after a knock on from Diego Dalot, who impressed in a midfield role.
Young's finish seven minutes from time ended any hopes of a late comeback in south east London.
