Manchester United sacked manager Louis van Gaal on Monday after an FA Cup triumph failed to make up for the club's inability to qualify for the Champions League amid widespread discontent with a season of insipid performances.

The Dutchman was dismissed two days after United's win over Crystal Palace in the Wembley Cup final, their first trophy in three years, paving the way for the widely-expected appointment of former Chelsea boss Jose Mourinho as his successor.

News of Van Gaal's impending departure from the club leaked out minutes after Saturday's 2-1 extra-time victory over Palace and, following relentless media speculation and a day of negotiations, it was confirmed by both sides on Monday evening.

"I'd like to thank Louis and his staff for their excellent work in the past two years culminating in winning a record-equalling 12th FA Cup for the club," executive vice chairman Ed Woodward said in a statement on the website of the club owned by the American Glazer family (www.manutd.com).

"He has behaved with great professionalism and dignity throughout his time here. He leaves us with a legacy of having given several young players the confidence to show their ability on the highest stage."

Van Gaal, though gushing in his appreciation of the chance to manage the club, was not so happy to be moving on.

"I am very disappointed to be unable to complete our intended three-year plan," he said.

"It has been an honour to manage such a magnificent club as Manchester United FC, and in doing so, I have fulfilled a long-held ambition.

"I have been privileged during my management career to have won 20 trophies but winning the FA Cup, which is steeped in so much history, will always be one of the most special achievements of my career."

That success, however, could not gloss over a season in which United finished fifth in the standings, missing out on Champions League qualification, and where dull performances had the fans booing their own team even after victories.

DISGRUNTLED FANS

After replacing David Moyes two years ago, Van Gaal got the team into the Champions League in his first season.

However, United's inability to produce the free-flowing football that characterised Alex Ferguson's trophy-laden reign eventually caused a rift throughout the club and in the stands.

For generations of fans brought up to expect high octane attacking football, Van Gaal's stultifying approach was hard to swallow, particularly when it did not work well, after he spent almost 300 million pounds ($434.34 million) on players.

This season's dire statistics, beyond the key one of fifth place, are a damning indictment of the Dutchman's tactics.

United scored 49 goals in 38 games, in contrast to their previous Premier League average of over 76 and fourth-placed Manchester City's 71.

They had the joint-highest number of goalless draws in the division, while Opta noted that United's 430 shots on target was 15th in the 20-team league and they made more backward passes than any other side.

It was not just supporters who were disgruntled either.

A story in Monday's Guardian newspaper said squad members had talked among themselves about openly defying the Dutchman's rigid tactical directions, which allegedly included instructions to players not to take first-time shots.

It also reported that the two most senior players, Wayne Rooney and Michael Carrick, had raised concerns with Van Gaal about his post-match "evaluation sessions" in which he publicly criticised players in front of their team mates

WIDESPREAD DISSATISFACTION

With such widespread dissatisfaction it easy to forget that the 64-year-old former Ajax Amsterdam, Barcelona, Bayern Munich and Netherlands coach was seen as the safe option when he was hired by United in May 2014 following Moyes's sacking.

He got the club back in the Champions League with a fourth-place finish but, despite heavy spending on the likes of Memphis Depay, Anthony Martial and Bastian Schweinsteiger, United stagnated after topping the table at the end of September.

French striker Martial apart, the new players struggled to justify their fees, and Van Gaal increasingly turned to talented youngsters such as Marcus Rashford, who has rapidly emerged from United's youth team to earn a place in the England squad.

By mid-December United were out of the top four after successive defeats by promoted clubs Bournemouth and Norwich City and they exited the Champions League after finishing third in a modest group behind VfL Wolfsburg and PSV Eindhoven.

At home to Southampton United were booed off the pitch and in Denmark the supporters, already frustrated by finding their team playing in the Europa League, chanted obscenities about how bad Van Gaal's side were in a 2-1 loss to FC Midjytlland.

Despite recovering with a 5-1 win in the second leg, United then lost to Liverpool in the round of 16.

A late challenge for fourth place, the Cup run and the fan-pleasing introduction of the youngsters, bought Van Gaal time but in the bigger picture it was not enough to change the mood.

Hovering in the background since his sacking in December has been Mourinho, once the scourge of Old Trafford for Porto and Chelsea but now seemingly about to be welcomed with open arms.

The Portuguese is hardly a graduate of the swashbuckling school of football himself but his remarkable record of success across Europe, combined with a larger-than-life personality, mean that, if he is appointed, United fans will at least be able to look forward to next season rather than dreading it.