Colin Montgomerie believes that Tiger Woods could be risking his long-term fitness if he plays through back injury pain in this week's US PGA Championship.
The former world number one has until 10 minutes before Thursday's tee-off time to decide on whether to feature in the tournament.
The 38-year-old was forced to abandon Sunday's WGC-Bridgestone Invitational midway through the final round due to his back problem.
"How can he play again this year, never mind within three days?" Montgomerie told BBC Radio 5 live. "This is a big golf course and the rough is heavy again.
"He's hitting the ball, I hate to say, not straight. He will be in the rough and he will suffer. Whether it's good for his long-term future in the game to play here or not, I am not sure."
Woods returned to action in June after spending three months on the sidelines following back surgery.