Andrew Todhunter is going to have to wait to make his UFC debut.

The former U.S. Army sniper had to pull out of his fight against Albert Tumenov at UFC 188 on Saturday in Mexico City on Thursday night when doctors deemed him unfit to compete, the UFC announced. The fight will be canceled altogether since it's too late to find Tumenov another foe.

Ed Kapp, a rep from Todhunter's Team Guardian management firm, told MMAFighting.com that Todhunter passed out trying to make weight. UFC officials noticed the issue and alerted doctors, who administered IV fluid, Kapp said.

Todhunter, 27, took the bout on less than two weeks notice when Tumenov's original opponent, Hector Urbina, withdrew due to injury.

Todhunter (7-0), an undefeated prospect with every win coming by finish, competed in a boxing match at 200 pounds less than a month ago May 15. He told MMAFighting.com in an interview last Friday that he was still pretty far off the 171-pound welterweight maximum, but was very confident he would hit the mark. Todhunter said he lost 38 pounds in four days once before a fight and finished his opponent in the first round.

In the interview, Todhunter said he was disappointed his first UFC bout wasn't on better terms.

"That's the only part that sucks about this fight," Todhunter said. "I really wanted to come to the UFC in tip-top shape and really make a statement. But you don't always get it the way you want it. But I'm still gonna make weight and I'm still gonna fight. It's gonna be a good experience."

Tumenov (15-2), a Russian prospect, has won three straight UFC fights and was coming off a unanimous decision victory over Nico Musoke at UFC on FOX 14 in January.

"This is a really unfortunate situation, but health is the No. 1 priority," Todhunter's manager Charles McCarthy said in a statement. "Andrew was excited as anyone I've ever seen to make his UFC debut. But I know he'll be back soon and he'll make a major impact when he is."