Brock Lesnar Returns To WWE One Month After 'Retirement,' Rips Pants In Match

Brock Lesnar pulled a Tom Brady at "WWE Raw" on Monday -- the Beast Incarnate "unretired" and got revenge on Oba Femi just weeks after seemingly ending his career at WrestleMania ... but the iconic moment wasn't without issue.

The chaos unfolded at First Horizon Coliseum ... as Lesnar attacked Femi at the start of his open challenge, hitting his foe with several F-5 finishers as payback for the loss he suffered in Las Vegas last month.

After the last painful move, Lesnar sat next to a wincing Femi ... and his positioning might've had something to do with the fact he busted his jeans wide open during his brutal beatdown, exposing his undies in the process.

Lesnar has had serious issues in the pants department over the years ... and this is hardly the first time he's dealt with his jeans falling apart.

The return now sets up an epic showdown at Clash in Italy ... even though Paul Heyman said later in the night his guy is still retired.

Who knows what to think anymore -- after all, Heyman told TMZ Sports before Mania he expected Lesnar to dominate for years to come.