During a recent interview with Yahoo Sports, UFC middleweight champion Michael Bisping stressed the importance of defending his title against the top contender.

At the time, there were reports circulating that former welterweight champion Georges St-Pierre was ending his three-year Octagon hiatus and returning to action in 2017. And while Bisping’s name was being included among potential candidates to face GSP, the veteran mixed martial artist didn’t seem overly enthusiastic about the possibility of making his second title defense against the MMA’s greatest welterweight.

Bisping wouldn’t detail his reasons to Yahoo Sports for not being eager to face St-Pierre, but now that UFC president Dana White has announced that the fight is official — a date has not yet been set — Bisping is speaking out.

“Georges St-Pierre is straight-up crazy if he thinks he’ll be able to stroll off the couch after a three-year break and beat him …” the 37-year-old told TMZ Sports on Thursday.

“The guy’s out of his [expletive] mind!”

At first blush, Bisping’s comments might appear disrespectful. St-Pierre, 35, has had a distinguished professional MMA career. He’s compiled an eye-opening 25-2 record against the very best 170-pound fighters UFC had to offer.

But Bisping (30-7) might represent the toughest test of St-Pierre’s career. GSP will enter the cage with distinct disadvantages. He faces a champion who is significantly larger and stronger. Bisping was a light heavyweight contender before finding his greatest success at middleweight. And GSP hasn’t fought competitively since 2013.

Most fighters, who’ve been out of action for a while, usually opt for a tune-up bout. Not GSP, who’s walking directly into the fire and doing so at 185 pounds.

No one knows how GSP’s body will respond to the extra weight on fight night. Will he sacrifice speed, stamina and strength? If so, this could prove disastrous against Bisping, who will be fighting for the fourth time since 2016.

But this is GSP, who should never be underestimated, despite his extended layoff. While Bisping has reason to be optimistic, he is smart enough not to underestimate this opponent and St-Pierre has opened as a slight favorite as a result.