Ben Affleck ... childhood pal Matt Damon is "upstaging him" with his rock-solid abs. Topless pictures of the 54-year-old Hollywood star on the set of Christopher Nolan's new movie 'The Odyssey ...

Of course, being in what is possibly the longest-standing Hollywood bromance ever means that even if Affleck and Damon disagree ... a great movie. That’s one of the things about Matt that ...