The Blues' hopes of finishing third or fourth looked doomed after Wednesday night's defeat to Newcastle that left them four points adrift with just two games remaining, but the Magpies' loss to Manchester City and Tottenham's draw at Aston Villa on Sunday - coupled with Arsenal's failure to beat Norwich on Saturday - kept alive sixth-placed Chelsea's slim hopes of qualifying for next season's Champions League via the Premier League.
They must beat FA Cup final opponents Liverpool for the second time in four days to stand any chance of overhauling two of the three teams directly above them.
Mata said of the clash at Anfield: "We have to win and still believe in playing the Champions League next year."
Mata insisted there was no chance of him suffering burnout ahead of what could be more overtime for the winger.
The 24-year-old said: "I have plenty of energy left. It's a long season and my first in England, but the benefits of winning easily outweigh the fatigue."