Chelsea have progressed into the quarter-finals of the FA Cup with a 2-0 win over Birmingham City in Roberto Di Matteo's first game in charge of the club.
Chelsea began strongly when Mata was denied after three minutes, but the home side eased their way into the game, with Petr Cech having to make a couple of fine saves to keep the score level.
It was the Premier League side that eventually broke the deadlock, however. Less than ten minutes into the second half the ball fell to Mata, who stabbed it home from ten yards.
Chelsea doubled their lead five minutes later through a long-range strike from Raul Meireles that gave goalkeeper Colin Doyle no chance.
It could have been 3-0 just ten minutes later when Guirane N'daw brought down Fernando Torres in the penalty area, but Mata saw his resulting penalty saved by Doyle.
Chelsea continued to press for a third, however, and came close yet again when Daniel Sturridge couldn't finish from five yards after being found by Torres.
The result means that Chelsea will host Leicester City in the next round of the FA Cup.