"We need to move on and come back next week stronger. It was not a good performance and not a good result, obviously."
United are at home to West Ham in the FA Cup quarter-finals on Sunday and the 27-year old playmaker - who will miss the match due to the red card he earned in the 1-0 defeat at West Bromwich Albion - acknowledged the competition was their best chance of salvaging something from a poor season.
"The FA Cup is very special for all of us and we need to recover as soon as possible. Then, after the weekend, we can look at the Europa League again."
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United face a mammoth task to overturn the two-goal deficit when they meet Liverpool at Old Trafford in the return leg on Thursday, but Mata was confident it would not be mission impossible.
"We never give up," he said. "It's going to be tough because they are a good team with a good manager, but we could do it with our fans at home."
Defender Chris Smalling rued a toothless display which denied United even a sniff at the vital away goal.
"We're disappointed. I think we could have done with getting an away goal -- we know we've got a difficult job on our hands," Smalling told the club's website.
"We could have really done with getting that away goal. I think if you get that goal, you can be a bit more positive, but it's now up to us to rectify it in front of our own fans. The first goal is going to be crucial."
Louis van Gaal's men are sixth in the Premier League, three points behind fourth-placed Manchester City, who have a game in hand.
(Reporting by Zoran Milosavljevic in Belgrade and Shravanth Vijayakumar in Bengaluru, Editing by Sudipto Ganguly and Angus MacSwan)
