The attacker, whose goal against Manchester United on Sunday put the Blues into third place, tells his teammates that it must contain the Welsh winger at Stamford Bridge
"We are aware that there's still a job to do," the Chelsea star wrote on his blog, grada360.com. "This coming Wednesday against Tottenham [it will be] another final. It will be nice to meet Andre [Villas-Boas] at Stamford Bridge.
"Obviously, it's a vital game for both teams and we will have to watch one of the best players in the world: Gareth Bale.
The London clubs come face-to-face at Stamford Bridge with Spurs knowing that a win would put them level on points with their hosts, though the Blues' goal difference is significantly better.
Mata, whose 19th goal of the season on Sunday was enough to see off Manchester United, knows that PFA Player of the Year Bale, who netted his 20th of the Premier League campaign against Southampton, poses a big threat to the Blues.
"He [Bale] is in an amazing shape and proves to be a decisive player for Spurs almost every week. I take this opportunity to congratulate him for all his recent awards," Mata explained.
"So it's going to be tough but, with the support of the Bridge, I think we can make it and seal our place in next season's Champions League."