Tiger Woods withdrew from the 28th Omega Dubai Desert Classic an hour before his scheduled second round tee time Friday with back spasms he began experiencing late the previous night, his agent Mark Steinberg has confirmed.

Steinberg said the lower back issue was not related to the three surgeries Woods has had on his back, the last of them in August 2015.

“He says it’s not the nerve pain that’s kept him out for so long,” Steinberg said.

“He says it’s a back spasm and he just can’t get the spasm to calm down. So that’s where we are. Feels terrible. [He] talked to Matthew [Fitzpatrick] and Danny [Willett], feels awful, and he feels terrible for the tournament.”

Woods told reporters “I wasn’t in pain at all” after his opening five-over 77 at Emirates Golf Club Thursday but clearly looked troubled, walking with a cautious gait and finishing his swing with a stiff, ungainly looking finish. With the projected cut at around +1 given Friday’s wild winds, Woods would have needed to fire at least a 68 to survive the weekend, a feat that looked beyond him after a first round punctuated with poor approaches, sloppy chipping and tentative putting.

Steinberg said the 14-time major champion had tried to ease the issue late last night and spent a further 3.5 hours with his trainer Friday morning without success, forcing his scratching from a tournament he was won twice before. He had suffered from spasms recently, Steinberg confirmed. “No doubt about it.”

“Spasms are a funny thing. I’m certainly no doctor but they come and go. And again, the fact that he feels as though it’s not the nerve pain, that’s very encouraging for him,” said Steinberg. “He can move around. He [just] can’t make a full rotation on the swing,”

Woods had not pinpointed a specific trigger to the spasms. “Look, he doesn’t have the strongest back in the world, right. So it’s probably easier to spasm because of the — because of the issues he’s had. So I’m sure there’s a variety of factors that can play into it,” Steinberg said.

The 41-year-old teed it up in Dubai, for a reported seven figure appearance fee, a week after his 2017 bow at the Farmers’ Insurance Open at Torrey Pines in San Diego where he missed the cut by four shots. His round off 77 was his worst in 29 competitive rounds on the Majlis course at Emirates GC.

Now ranked 666th in the Official World Golf Rankings, Woods has also committed to two other PGA Tour events as part of his comeback from multiple back surgeries with the aim of being ready for the U.S. Masters at Augusta National in April. Steinberg said Woods was still aiming for the Genesis Open at Riviera Country Club in California (February 16-19) and The Honda Classic at Palm Beach Gardens, Florida (February 23-26) although his participation is now clearly in doubt.