Marc Anthony — Set To Battle Justin Bieber … on ‘X Factor’

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Watch out Justin Bieber — Marc Anthony took a cue from your playbook and just signed up to be the next celebrity mentor on “X Factor” … LET THE BATTLE BEGIN.

Sources close to Marc tell us … he recently inked a deal with the FOX talent show to join the cast as a mentor for Simon Cowell”s group of music hopefuls … the pair has been friends for years.

If you recall, Bieber also signed on to be a celeb mentor — there will be 4 in total, one for each judge — lending his (ahem) years of knowledge to L.A. Reid“s squad.

So here”s how they match up … JB has sold 15 million albums to Marc”s paltry 12 million … Marc has two Grammy”s compared to Justin”s zero … BUT — they”ve both dated hot Latin chicks.

May the best man (or boy) win.