And Mata is expecting Celta to provide a tough test for United, despite his side being strong favourites to book a place in the competition's final on May 24.
"Two big challenges await us this week," Mata wrote in his weekly blog on the United website. "First of all we have to visit Celta in the Europa League.
"I can say, without exaggerating, that they are one of the teams that play better football in Spain, and not only this season. Being back home will be special, but very difficult at the same time. We must perform at our best in order to beat them.
"Besides, a few days later we will visit another big opponent, Arsenal, with three key points at stake. Every game from now on is a final for us, that's how we face them."
Mata made a surprise early return from a groin injury to be named on the bench against Swansea and the Spain international was glad to be back despite United drawing at home for the 10th time in the league this season.
"This week we're having a mix of good and bad feelings once again, the latter being, of course, the draw against Swansea and Luke [Shaw] and Eric's [Bailly] injuries," Mata wrote.
"In this regard we're being very unlucky, but we have to keep looking ahead. As for the game, we let two points slip away, again, when the win was so much needed.
"But there have been very good moments during the week as well, such as my being back with the team, and also my birthday. Thank you so much to all of you for your messages, it was a great day and, although I didn't get the present of the three points, I hope we can have a great season ending in the remaining few weeks.
"As regards to my recovery, I'm very happy and looking forward to helping the team in such an important moment of the year, enjoying myself on the pitch and, hopefully, lifting another trophy."