Ole Gunnar Solskjaer and Frank Lampard put their Premier League top-four battle on the backburner for the day as the club greats focused on securing the chance to bid for more of the sort of silverware they collected so much of during their playing days.
United had won the season’s previous three meetings between the sides but Chelsea comprehensively triumphed in Sunday’s semi-final, with De Gea in the firing line after his role in Olivier Giroud and Mason Mount setting up a 3-1 win.
Solskjaer could have few complaints after seeing his side’s 19-match unbeaten come to an abrupt halt in the capital, where the United manager’s decision to change the system and make five alterations backfired.
De Gea was among those to retain their places as cup goalkeeper Sergio Romero was spurned and the United shot-stopper will have been disappointed not to prevent Giroud flicking past him after too easily beating Victor Lindelof.
That goal came 11 minutes into first-half stoppage time, played due to Eric Bailly having suffered a nasty-looking head injury, and Chelsea compounded matters 43 seconds into the second half at an empty Wembley.
De Gea will have nightmares about Mount’s low shot creeping past him, with captain Harry Maguire’s own goal summing up a poor performance on a night when Bruno Fernandes’ penalty proved scant consolation.
But the Red Devils were producing precious little and Mount flashed over, with De Gea stopping a deflected Giroud attempt as Chelsea looked to rubberstamp their date with Arsenal.
De Gea also stopped James but United failed to effectively clear, with Maguire directing past his own goalkeeper as he tried to stop Antonio Rudiger reaching a cross from Alonso.
That 74th-minute goal ended any faint hopes of a comeback and play petered out, even after Fernandes scored a late penalty after Callum Hudson-Odoi hacked Martial down in the box.