Tony Hawk -- Bieber Pulled Off Skate Trick ... That I Could NEVER Do!

Time to have your friggin' mind blown ... 'cause Tony Hawk says there's something Justin Bieber actually does BETTER than him on a skateboard ... and he' s totally serious.

Tony stopped by "TMZ Hollywood Sports" to talk about his new video game "Tony Hawk's Pro Skater 5" when the topic turned to celebrity skaters ... being that Lil Wayne is a playable character in the game.

After giving Wayne some big time skate props ... Tony drops a 4-wheeled bombshell ... saying he's actually witnessed Justin do something that in all his years of skating ... Hawk has never pulled off.

"He impressed me with an inward hardflip," Hawk said ... "It's a trick I've never been able to do in my life."

"He pulled one right in front of me and I was like, 'All right, there it is.'"

But one trick doesn't put you in the Hall of Fame -- 'cause when we asked Tony if Bieber will be a playable character in the game, it didn't sound like JB made the cut.

BTW -- Here's footage of what an inward hardflip looks like ...