Ole Gunnar Solskjaer saw Manchester United ’s brief revival ended by Reds reject Joshua King.
The Bournemouth forward, 27, produced an outstanding goal on the stroke of half time – lifting the ball over Aaron Wan Bissaka before volleying past David de Gea.
The win sent Eddie Howe’s men above United in the Premier League table to pile the pressure back on to Solskjaer.
King spent four years with the Norwegian’s reserves at Old Trafford. But he appeared just once in United’s senior team, in the League Cup.
He left on a free for Blackburn in 2013 before joining Bournemouth for £1million four years ago.
United had arrived on the south coast on the back of their best run of form since Solskjaer was handed the manager’s
job full time.
The Red Devils had been unbeaten in all competitions since returning from the international break.
They followed a 1-1 draw against league leaders Liverpool with wins over Partizan
Belgrade, Norwich and Chelsea to reach the quarter-finals of the Carabao Cup.