David de Gea says Manchester United's players are struggling to get over the "unexpected defeat" against West Brom.
Liverpool's win over the Cherries last Saturday - and United's subsequent loss to the Baggies - has cut the gap between them and second-placed United to one point, and De Gea says it makes their trip to the Vitality Stadium a must-win game.
"It was a tough one to take; it was a real blow and we're all a bit down," De Gea told MUTV.
"It was such an unexpected defeat but the good thing is we have got a game coming right up on the back of it.
"It is a real chance to lift ourselves and get back to winning ways."
Jose Mourinho intends to make changes ahead of Saturday's FA Cup semi-final against Tottenham but De Gea says the runners-up spot in the Premier League remains a target.
"What we have got to make sure of now is that we finish second this season," he said. "That's what we've got to hope for league-wise.
"We've got to make sure we put in a good performance and get the win midweek and make sure we hold on to that second place."
Bournemouth have won one of their last eight fixtures, a 2-1 success over West Brom on March 17, but De Gea is still expecting a stern test.
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"They've had a really good season, especially in the performances and the results they've gained at home," he said.
"They're quick all over the field, they've got some speedy forwards. Quite a few of the front players have got a good eye for goal, as well.
"It's not an easy place to go. It's quite a small, compact place, a difficult ground to go and get a result.
"All that considered, we've still got to make sure that we perform well to try and get those three points. That's the key."