The Red Devils suffered their first defeat in five games following a 1-0 loss to the Baggies at The Hawthorns after Salomon Rondon’s second-half winner.
We have to keep believing in ourselves to achieve the goals that are still in our minds
Mata was criticised by his manager Louis van Gaal after he was sent off inside 26 minutes following two yellow cards.
The 20-time English champions had beaten Shrewsbury Town, FC Midtjylland, Arsenal and Watford before their defeat at West Brom.
Writing on his blog on Monday morning, Mata explained why he is confident United can end the season on a positive note ahead of Thursday’s game at Anfield.
“The team was in a good shape,” Mata wrote.
“I hope this blot won’t make us forget that we were on the right track, and that we have to keep believing in ourselves to achieve the goals that are still in our minds from now until the end of the season.”
Van Gaal’s side make the trip to Liverpool in the first leg of their Europa League last-16 clash on Thursday night.
The Red Devils are in sixth place and six points behind fourth-placed Manchester City, who occupy the final Champions League spot.
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