They face each other again in the Capital One Cup but Mata is adamant that advancing to the quarter-finals is the only revenge the Blues are interested in.
Mata, who scored his side's second goal on Sunday, said: "We're obviously disappointed after our defeat.
"It was a very important match for us, first v second, and we were eager to win in order to open a gap at the top of the table.
"But football keeps going, there is no time to look back.
"We are again facing United, again at Stamford Bridge, and I hope we can win and forget the defeat."