"It's a tricky stadium, and the wind was not a good help to play football, but I honestly think that we didn't deserve to lose," Mata wrote in his online blog. "We were really unlucky with their first goal, and it reflects what the game was.
"We had good chances, yet we couldn't score. We went back home with no points, feeling that we just can't lose this kind of games again.
"I hope that piece of luck we are missing will come to our side, because we are struggling even with injuries."
United are seven points behind a Champions League spot.