The result means victory for Chelsea against Tottenham at Stamford Bridge on Wednesday will seal a top-four spot thanks to their superior goal difference.
And Mata, who has now scored 19 goals in all-competitions this season, insists they are well poised for UEFA Champions League football next season.
"It was a very, very important victory for us," the Spaniard told Sky Sports. "It was like a final and we have another great game to come next week, so we will try to win and get closer to our aim, which is third.
"It is true that I am scoring more goals than ever and I'm really happy. The only thing I want is to keep scoring and keep up my assists to help my team until the end.
"We have three more Premier League games to play and the only the thing we want is to win every game because I think Chelsea deserve to play in the Champions League next season.
"If we play like we did today then I think we can do it."