United beat Bournemouth 3-1 in their final fixture on Tuesday – a game held over from Sunday due to a bomb scare – but it was not enough to take them into the Champions League places as they finished below fourth-place Manchester City on goal difference.

United must now beat Crystal Palace in Saturday’s FA Cup final to salvage something from their season and there were ripples of dissent towards Van Gaal in the form of boos as he began a post-match address to a thin home crowd.

But despite persistent speculation linking Jose Mourinho with his job, when asked if he would still be in place on the first day of next season, Van Gaal, who took over at United in 2014, replied: “Yes. Because I have signed a three-year contract.”

Van Gaal conceded that United’s fifth-place finish represented a “step back”, but said that Leicester City’s title triumph proved that anyone could win the title next season.

Needing a 19-goal win to pip City to fourth place, United had to wait until the 43rd minute to go ahead as Marcus Rashford dummied Anthony Martial’s pass for skipper Wayne Rooney to tuck away his 100th league goal at Old Trafford.

Rashford, named in England’s provisional Euro 2016 squad on Monday, made it 2-0 by thrashing home from Antonio Valencia’s knockdown and Rooney then freed substitute Ashley Young to add a third.

But in stoppage time Chris Smalling sliced Max Gradel’s shot into his own net to gift Bournemouth a goal that prevented David de Gea from earning a share of the Golden Glove – awarded to the goalkeeper with the most clean sheets — with Arsenal’s Petr Cech.

Van Gaal described the goal as “an irritation”.

United finished the campaign with just 49 league goals to their name — their worst tally since 1989-90 — and despite decrying perceived poor fortune with penalties, Van Gaal could not disguise his team’s attacking shortcomings.

“Defensively we are one of the best teams in the Premier League, but attacking-wise we have to improve,” he said.