Former WWE star CM Punk was expected to make his UFC debut this summer, but those plans are on hold as the 37-year-old is scheduled to undergo back surgery this week.
UFC president Dana White told ESPN that CM Punk "won't be out long."
According to MMAFighting.com, CM Punk, whose birth name is Phil Brooks, has been suffering from a back injury he believes is related to his long professional wrestling career and still intends to make an appearance in 2016.
CM Punk (0-0) was in Las Vegas last weekend to see UFC newcomer Mickey Gall (2-0) pick up a first-round win. The two were expected to square off in June, but CM Punk will now require more time.
"My back has always bugged me," CM Punk told MMAFighting.com. "Figured it was just wrestling s---. Turns out it was.
"It got bad enough to the point where I couldn't do anything the week before I went to train with the New Jersey Devils last month. One day I could manage, the next day I couldn't. I've been in agony for almost a month. Chiropractor, acupuncture, massage, cryotherapy -- nothing worked."
This is the second injury setback for CM Punk, who last fall missed several months of training at Roufusport MMA in Milwaukee with a shoulder injury.
CM Punk signed with UFC in December 2014, despite no background in martial arts. White targeted the 24-year-old Gall as a potential opponent after his professional debut in Philadelphia late last year. Gall has predicted he will finish Punk in one round.