AKRON, United States (AFP) - Former world number one Tiger Woods withdrew from the final round of the World Golf Championships Bridgestone Invitational on Sunday, casting serious doubt on his status for the upcoming PGA Championship.

The final major championship of the year tees off in four days at Valhalla Golf Club in Louisville, Kentucky, and Woods was hopeful it might signal a return to form as the 14-time major champion chases the career record of 18 majors won by Jack Nicklaus.

Woods, 38, underwent back surgery March 31 to relieve pressure on a pinched nerve and this was only this third event since the operation.

He missed the cut at the PGA event he hosts in Washington in late June and finished level 69th at the British Open last month, his worst showing in a major as a professional.

At the time Woods withdrew, he was three-over par for the final round at Firestone Country Club - where he has won eight times before - and stood four-over for the tournament.