Manchester United's problems mounted as the managerless Red Devils crashed out of the FA Cup after a 2-1 defeat against Brighton on Sunday.

Brajan Gruda put Brighton ahead in the first half at Old Trafford and former United striker Danny Welbeck netted after the break.

Benjamin Sesko's reply came too late to save his side from a third round exit as United teenager Shea Lacey was sent off in the final moments.

United were barraged by jeers from furious fans following the latest miserable result in another troubled season.

Caretaker boss Darren Fletcher has failed to stop the rot following Ruben Amorim's shock sacking on Monday, with United looking to appoint an interim manager until the end of the season

Former United boss Ole Gunnar Solskjaer and Michael Carrick, a decorated ex-United midfielder, have both been linked with the temporary role.

But regardless of United's past pedigree, the chaos enveloping Old Trafford hardly makes it an appealing job for any manager of stature these days.

Welbeck, 35, was at United when they won their most recent Premier League title in 2013 under Alex Ferguson, who watched the Brighton debacle from the directors box as the current generation showed how far they have fallen from the Scot's golden era.

United, currently a disappointing seventh in the Premier League, are without a win in four games and have managed only one victory in their last seven matches.

That wretched form is unlikely to improve anytime soon with United hosting Manchester City next weekend before travelling to Premier League leaders Arsenal on January 25.

After a humiliating League Cup loss at fourth tier Grimsby in August, United have exited both domestic cups at the first hurdle for the first time since 1981-82.

Avenging their 2023 FA Cup semi-final loss to United, Brighton have now won on four of their last five visits to Old Trafford. (AFP)