With United set to lose £50m in revenue if they fail to qualify for the Champions League, Mourinho knows the importance of Wednesday's final.
Manchester United gave four players their first Premier League starts and a youthful team beat Crystal Palace 2-0 on the final day of the season on Sunday.
- Paul Pogba netted his first Premier League goal since December by scoring in this game. The other debutants were Joel Pereira, Scott McTominay and Demetri Mitchell.
"Our postponed fixtures accumulated to the last month of the season, and in the last two months of the season we have played 16 matches". Rather than picking an easy pass to Rooney, the unflustered 21-year-old showed quick feet and confidence to make space and fire home superbly.
"I have seen in the football media that certain pundits can not understand why our players are exhausted".
Allardyce's men failed to muster a shot on target during a one-sided half that took on an exhibition feel towards the end, with Pogba and Lingard replaced by Michael Carrick and Anthony Martial before half-time.More news: North Korea's latest missile test called 'substantial advance'
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Mourinho handed youngster Gomes his debut in the closing stages of the second half, as United saw out the closing stages with relative ease.
Palace almost leveled matters 10 minutes into the second half when Wilfried Zaha picked out Christian Benteke, who sent a header against the crossbar.
After that, though, both sides were largely going through the motions, although Rooney almost injected intrigue when directing a free-kick just wide of his own goal before Pereira did brilliantly to not only stop a Luka Milivojevic free-kick but hold onto it.
Under Mourinho, United have signed the world's most expensive player, signed the Bundesliga player of the season, gone 25 games unbeaten, and still managed to finish lower than Van Gaal did previous year.
"He has not played for a long time and needs minutes on the pitch, so he plays against Palace".