Former World No. 1 Tiger Woods was reportedly forced to withdraw from the WGC-Bridgestone Invitational in Ohio midway through his final round due to a back injury.
Woods said that the problem occurred while he was playing his second shot from a difficult stance on the second hole, although he left the course on the ninth after his tee shot appeared to aggravate the injury.
Woods said that he just jarred it and it has been 'spasming' ever since, The BBC reported.
The injury has left The American's participation in the US PGA next week in doubt. Woods is due to play alongside fellow American Phil Mickelson for the first two rounds at Valhalla next week.
As well as potentially missing out on the final major championship of the year, Woods might face a race to be fit in time for the Ryder Cup in September.
The 14-time major winner underwent surgery in March, which caused him to miss three months, but Woods has reported no problems with his back since returning in June.
At the time Woods withdrew, he was three over par for the final round at the Firestone Country Club, where he has won eight times before, and was four over for the tournament, the report added.