Rees is a former world champion and has only lost once, but is still a big underdog against rising American star Broner.
However Calzaghe, who used to train Rees, believes that his fellow Welshman's ability to put pressure on Broner will stand him in good stead.
"I believe he's got a great chance," Calzaghe told Sky Sports News.
"Gavin's got a great ability to absorb shots, he can fire bullets and he throw punches in bunches.
"I've seen two clips of Broner, and really, he didn't impress me. When Gavin boxed Souleymane M'Baye [for the WBA title in 2007] he was an outsider and what did he do? He performed amazingly, and the same applies on Saturday night."
Rees said recently that he had no problem with being labelled the underdog for the fight, which takes place in Atlantic City at the weekend.