UFC's Luke Rockhold -- Weidman Fight Shoulda Been Stopped Sooner

UFC champ Luke Rockhold says he's SHOCKED his UFC 194 fight with Chris Weidman wasn't stopped a lot sooner than it was ... saying it was pretty clear Weidman was done in the 3rd.

Rockhold joined the guys on "TMZ Sports" on FS1 (tonight at 9 PM PT, 12 AM ET) -- and said when he rewatched the fight, he noticed the end of the 3rd round was especially one-sided.

"Going back and looking at it now, it was pretty brutal ... the unanswered punches I was delivering ... I was just thinking in my head, 'Is this man gonna stop it?'"

Even Joe Rogan was surprised referee Herb Dean let it go as long as it did -- as Rockhold rained down on Weidman it was a flurry of devastating punches. The fight was ultimately stopped 3 minutes into round 4.

Rockhold says he was also confused in between the 3rd and 4th round -- because he wasn't sure if the officials were going to let Weidman leave his corner and continue the fight.

There's A LOT more on the show tonight -- make sure to check out the entire interview on "TMZ Sports" weeknights on FS1 at 9 PM PT, 12 AM ET.