4:02 PM PT -- Tiger Woods' manager just told reporters at the event that the golfer began suffering from flu-like symptoms Thursday night, but decided to try to push through it all on Friday.

However, he became dizzy on the course ... and withdrew from the event.

Woods' manager, though, said that after an IV, the 48-year-old is now feeling "much, much better."

Tiger Woods' return to the PGA Tour was shortlived ... he just withdrew from The Genesis Invitational after suffering from an illness.

The Big Cat -- who shot a 1-over 73 at the tourney on Thursday in his first action since last April -- made it through six holes on Friday afternoon ... before he decided he just couldn't go anymore.

The golfing legend hit his tee shot on hole No. 7, then hopped in a cart and headed back to the clubhouse.

It's unclear the severity of his ailment ... although fans in attendance at the Riviera Country Club in Los Angeles have grown concerned for the 48-year-old after an ambulance showed up at the venue a short time after he officially called it quits.

It seems, however, a bug is going around the course ... as fellow PGA Tour star Jordan Spieth is reportedly dealing with some uneasy symptoms too.

This weekend's rounds were the first PGA Tour ones Woods has logged since he underwent surgery on his ankle following the 2023 Masters. He looked solid throughout Thursday -- although he did have one shank on the 18th hole that went viral.

Following the round, he seemed normal ... though he did tell Golf Channel he had "some treatment ahead of" him to get ready for Friday's 18.