Tiger Woods has been given until 10 minutes before he is due to tee off at the US PGA at Valhalla to decide whether he is going to compete in golf's final major of the season.
Woods withdrew from the final round of the WGC-Bridgestone Invitational at Firestone Country Club after with a similar back problem to the one which forced him to have surgery in April.
He was helped off the course by caddie Joe LaCava, who despite the injury remains optimistic the 14-time major winner will take part at Valhalla this week.
The 38-year-old has since been given a time extension on when he needs to declare if he is fit or not.
The registration deadline on the eve of tournament is generally set at 5pm the evening before the opening round, but Woods will be able to leave it until the course is at capacity and players are already out on the course before making up his mind.
Meanwhile, Bubba Watson was in no mood for a break from practising at the Jack Nicklaus-designed course after shunning an opportunity to take part in a longest drive competition.
Former Open champion Louis Oosthuizen won the contest, which was hosted on the 10th hole, with a 340-yard drive, but Watson instead chose to concentrate on his round.
"I want to practice the game of golf," said Watson. "I want to learn this golf course. I haven't seen the 10th hole. I don't see that we should have a competition like that while we're playing a practice round and learning the golf course, trying to win a great championship."