WEST HOLLYWOOD, Calif. -- Conor McGregor never intended to get into a sparring session with "The Mountain." It just kind of happened.

The UFC interim featherweight champion went toe-to-toe with 6-foot-9, 400-pound Hafthor Julius Bjornsson at SGB Ireland back in October. Video of the scene was captured and went viral. McGregor, who stands 5-foot-9 and fights at 145 pounds, said it all started when he asked for a photo op -- kind of like the famous picture of Bruce Lee facing off with Kareem Abdul-Jabbar.

"[I said,] 'Let's take a cool picture like that,'" McGregor said at a UFC 194 media lunch this week. "We squared off as if we were gonna do it. Then all of a sudden, he's bouncing and I'm bouncing. Next thing you know, we're having a full, bareknuckle body shot fight."

McGregor said it started out very lightly, but the two ended up going fairly hard.

"I was hitting him with some shots," McGregor said. "I had to hit him with some shots. He was trying to hit me as well. He wasn't taking it easy. He tried to grab me and tried to pull my head off. I defended, freed the head. I was like this motherf*cker is so big, I have to start smashing him to the body."

Bjornsson is an Icelandic strongman competitor best known for his role as Gregor "The Mountain" Clegane in HBO's "Game of Thrones." McGregor, whose teammate Gunnar Nelson hails from Iceland, said Bjornsson was a great guy. But he made no bones about who won the battle. McGregor said that's why he didn't get a call from a freaked out UFC president Dana White wondering why he was sparring with one of the biggest, strongest humans on the planet.

"No call, no," McGregor said with a laugh. "Because they saw who won, that's why. There should have been a check. Twelve million views that video got. There should have been a show money check at least."

In all, McGregor said he enjoyed the experience.

"It was a lot of fun," McGregor said. "That's a big man -- 6-foot-9, 400 pounds. And I still folded him up."