Well, it looks like Matthew McConaughey may not have the biggest muscles in the biz.
Because this fella's been hitting the gym with a vengeance.
So now he's not just a pretty face, but a darn chiselled dude too.
Yes, Zac Efron's the guy in question.
And just check out the High School Musical star's impressive set of muscles.
Gone is the weedy little lad with the pony tail.
Say hello to a sculpted wonder of weight work.
We bet Vanessa Hudgens doesn't mind being gripped in that vice of love.
Now, we only have one thing we're still wondering...
Who'd win in an arm wrestle between Zac and Matthew?
You know, bicep against bicep.
We don't know the answer, but we do know that's one muscle wrestle we'd referee any day.
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