LOS ANGELES (AFP) — Ailing superstar Tiger Woods withdrew in the second round of the Genesis Invitational on Friday in the latest setback for the 15-time major champion.

Woods' longtime business partner Rob McNamara said Woods had felt "flu-like symptoms" on Thursday night and his condition worsened until he called it quits after hitting his tee shot at the seventh hole.

"He had a little bit of a fever and that, and was better during the warm-up, but then when he got out there and was walking and playing, he started feeling dizzy," McNamara said.

The arrival of an ambulance at Riviera's clubhouse sparked further concern.

However, McNamara said Woods had responded to on-site treatment for dehydration and Woods left the grounds in a courtesy car.

"Ultimately the doctors are saying he's got potentially some type of flu and that he was dehydrated," McNamara said. "He's been treated with an IV bag and he's doing much, much better."

Woods' premature exit of his first official PGA Tour event in more than 10 months overshadowed another outstanding day for American Patrick Cantlay, who had an eagle and four birdies in a six-under par 65 and a 13-under total of 129.

Cantlay's five-shot lead over Australian Jason Day, Canadian Mackenzie Hughes and American Luke List matched the largest 36-hole lead in tournament history.

But all eyes were on Woods, who buried his face in his hands as he was ferried from the course in a golf cart in an abrupt end to his first tour event since he withdrew from the rain-delayed third round of the Masters last April.

Two weeks later Woods had right ankle surgery to address lingering pain from injuries suffered in a 2021 car crash.

Woods has played only nine official events in the last four seasons. He has missed the cut twice and withdrawn three times.

Woods, who had spinal fusion surgery in 2017, said Thursday that back spasms contributed to a surprising shank at the 18th hole of his one-over par first round.

But McNamara said none of Woods' ongoing injury troubles contributed to his withdrawal.

"Not physical at all, his back's fine," McNamara said. "It was all medical illness, dehydration… now the symptoms are reversing themselves now that he's had an IV."

Even if the illness is fleeting it has cost Woods valuable, and increasingly rare, tournament play.

The 48-year-old has said he hoped his various physical problems would allow him to play up to one tournament a month this year but on Thursday he admitted it remained to be seen if that would pan out.

"I'm hoping that's the case, hoping that I play that much," Woods said.

Playing partner Gary Woodland, himself returning after surgery to remove a brain tumor last September, said Woods "just didn't look right" throughout the round.

"It sucks," Woodland said. "Obviously everything's better with him there and for him (to play) his first tournament back and he couldn't come out and finish the way he wanted to, that sucks for all of us."

Woods would have been battling to make the cut in the elite event. He opened Friday with a birdie at the par-five first but bogeyed the fourth and fifth and was two-over for the tournament.