According to Manchester United manager Jose Mourinho, all his players will attend the final.
Van Gaal was sacked as United boss 12 months ago, just days after he won the FA Cup final and was replaced by Mourinho.
There is certain to be a lack of cohesion to aspects of the Red Devils' play and Palace arrive at Old Trafford after following up a 5-0 defeat at Manchester City with a 4-0 victory against Hull.
Zlatan Ibrahimovic insists he is ready for Manchester United's appearance in the Europa League final - but he will probably have to towel off first.
The Portuguese believes one thing such a schedule has done is foster a bond within his squad, which is why he is so keen for Ibrahimovic and fellow injured players Ashley Young, Luke Shaw and Marcos Rojo to be present.
"It's great to have people talking about the club again, to reinvent and get to know Ajax again".
"If we are going to win the Europa League final it will be an unbelievable season for us, because have already won two trophies, and this one would be the third one", he added. "I know that my father will support me a little bit more than Ajax on Wednesday".More news: Russia Probe Names Current White House Official as 'Significant Person of Interest'
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Mourinho has named eight players who could make their debuts in his squad for Sunday's last Premier League game of the season against Crystal Palace.
Mourinho, meanwhile, has praised Wayne Rooney's professionalism amid one of his most hard seasons at Old Trafford.
"Paul Pogba is fine - strong guy, strong mentality", Mourinho said. "He plays against Palace".
Mourinho said: "Sometimes the players understand the situation, sometimes they still feel they are 24 or 25".
"We bring the ones who are more adapted to our team at the moment".
No matter how Mourinho spins it, the season was a failure for a club of Manchester United's stature which should be challenging for the Champions League trophy with the Bayerns and Real Madrids of the world, not losing timidly to Tottenham Hotspurs. They've been somehow more inconsistent than United this season.
United manager Jose Mourinho has prioritised the Europa League at the expense of securing a top four finish in the Premier League, but will his gamble pay off?