US captain Tom Watson said that Tiger Woods' latest back injury "doesn't bode well right now'' for Woods playing in the Ryder Cup.
Watson told SiriusXM PGA Tour Radio he was watching the final round of the Bridgestone Invitational when Woods withdrew after hitting his tee shot on the ninth hole because of another injury to his back.
"Tiger would be a great addition to our team,'' Watson said. "As I've said all along, I would pick Woods if he's healthy and playing well. This doesn't bode well right now. I just hope that maybe it's just an isolated problem that he can turn around and possibly play this week at the PGA.''
Woods flew home to Florida on Sunday to be evaluated. It was not clear when he would know if he could play at Valhalla, where he won the PGA Championship in 2000.
Woods, in only his third tournament since returning from back surgery, said he jarred his lower back when he hopped into a deep bunker after playing an awkward shot from the slope on the second hole at Firestone.
He tried to keep playing and hit some shockingly bad shots - one into the water on number three, another on the par-3 fifth that was 65 yards short of the flag.
Watson said he sent Woods a text message to tell him he was sorry about the injury, and "I hope you get well soon".
Woods missed two majors and three months of the season after March 31 back surgery.