The France international spoke glowingly of the Argentina international, and expects a difficult encounter against the Spanish champions at San Siro
The France international feels that the Spanish champions are the best team in the world, but insisted that the Rossoneri will do their utmost to progress.
"It's already difficult enough to stop Messi on Playstation," Mexes jokingly said in an interview with Sky Sport.
"Messi is a great player and he deserves respect, but we will play like we have always done. Barca are the best team in the world, but we will do everything we can to advance. We had to meet them sooner or later."
The former Roma centre-back then went on to admit that the absence of Thiago Silva is a huge blow for Milan.
"Thiago Silva is suffering a lot. We hope that his injury is not that bad because we need him. Hopefully he'll return sooner than expected."