Erik ten Hag began his time in charge of Manchester United by leading the Red Devils to his first Premier League game in charge on Sunday, but Brighton & Hove Albion spoiled the Dutchman's party.
Match Report
With Cristiano Ronaldo watching on from the bench, Graham Potter's team were by far the better side in the opening stages.
Pascal Gross was the man to break the deadlock with two goals in the space of nine minutes before half-time.
For the first, it was Gross who tapped in as Danny Welbeck cut through United's defence on his return to his former club, before pulling it back to the German to convert.
Minutes later, Solly March's effort from the right flank could only be palmed away by David de Gea and Gross was ready to pounce on the rebound.
Second-half fight-back
Ten Hag looked to change things up in the second half, calling on Cristiano as a substitute, with Christian Eriksen dropping into midfield after playing the first hour as a false nine.
The Portugal international did not have the desired impact though, and United could only pull one goal back.
A corner saw Diogo Dalot and Harry Maguire challenge Robert Sanchez in the Brighton goal, with Alexis McAllister inadvertently turning the ball into his own net.
Brighton managed to see out the result to secure their first ever league win at Old Trafford, with Gross becoming the first Brighton player ever to score two against Manchester United.
Match Events
0' The match is about to start!
6' MISS! Bruno's shot flies into the sky
18' Ferguson watches the game in stands
29' GOAL! Man Utd 0-1 Brighton (Gross)
38' GOAL! Man Utd 0-2 Brighton (Gross)
40' Ronaldo warms up on the sidelines
46' Yellow Card! Martinez booked
49' CHANCE! Welbeck's header over the bar
53' Sub! Ronaldo replaces Fred
60' CLOSE! Rashford misses a golden chance
67' OWN GOAL! Man Utd 1-2 Brighton (Mac Allister)
78' Sub! Van de Beek replaces McTominay
Line-ups
Man Utd XI: De Gea, Eriksen, Maguire, Fred, Shaw, Bruno Fernandes, Dalot, Rashford, Sancho, Martinez, McTominay
Subs: Ronaldo, Heaton, Varane, Van de Beek, Wan-Bissaka, T. Malacia, Garner, A. Elanga, Alejandro Garnacho
Brighton XI: Lallana, Webster, Welbeck, Gross, Veltman, Dunk, Trossard, March, Robert Sanchez, Mac Allister, M. Caicedo
Subs: Steele, Maupay, D. Undav, E. Mwepu, K. Mitoma, Jeremy Sarmiento, Tariq Lamptey, J. van Hecke, Levi Colwill