Tiger Woods was forced to withdraw from the Omega Dubai Desert Classic before his second round on Friday due to a bad back.
The 14-time Major Championship winner was making his first European Tour appearance since the 2015 US PGA Championship after a long spell out due to back problems and sometimes appeared to be in discomfort while shooting an opening 77.
Woods insisted after his round that he was not in any pain while out on the course but took the decision to withdraw on Friday morning sitting 12 shots behind overnight leader Sergio Garcia at five over.
"He felt okay coming off the golf course yesterday so he wasn't in pain," said Woods' agent Mark Steinberg.
"I didn't see him at dinner but he said he was okay and went into a spasm in his lower back, fairly late last night after dinner.
"He tried to work it out last night, didn't really get it worked out. He had treatment starting pretty early this morning for probably the past three, three and a half hours.
"He says it's not the nerve pain that's kept him out for so long. He says it's a back spasm and he just can't get the spasm to calm down. So that's where we are.
The short-term prognosis, he hopes he'll be strong based on the fact that it's not that nerve pain - Mark Steinberg
"He feels terrible, talked to Matthew (Fitzpatrick) and Danny (Willett), he feels awful and he feels terrible for the tournament. He wanted to be here. He wants to be here. He just feels terrible that he can't, you know, finish it out today.
"He can move around, he can't make a full rotation on the swing.
"The fact that he feels as though it's not the nerve pain, that's very encouraging for him.
"The short-term prognosis, he hopes he'll be strong based on the fact that it's not that nerve pain."
