(CNN) -- Tiger Woods may be clinging on to his world number one status but his participation in the Ryder Cup in Wales is in considerable doubt after a sorry performance in the WGC-Bridgestone Invitational tournament.
Woods finished 18-over-par at Firestone Country Club and his indifferent form has left him in 10th place in the U.S. Ryder Cup standings and outside the automatic picks.
If he cannot step up to the plate at this week's PGA Championship, Woods will need to rely on one of captain Corey Pavin's four selections and at the moment he does not believe he is worth a place.
"Not playing like this, definitely not, not playing like this," Woods told reporters when asked about the Ryder Cup.
"I wouldn't help the team if I'm playing like this. No one would help the team if they're shooting 18 over par."
But there is still time for Woods to turn around a season blighted by his self-imposed exile and now his poor form.
Pavin does not have to make his wild card selections until September 7 and Woods suggested: "I can turn it around by then."
Whether he can regain former glories while dealing with well-publicized problems in his personal life has divided opinion, but his display in a World Golf Championship event he has made his own, winning seven of the last 10 stagings, beggared belief.
He finished 30 strokes behind winner Hunter Mahan, who boosted his Ryder Cup chances, and he was blunt in his assessment of his play.
"I didn't drive it at all this week. My irons weren't very good again, and I made no putts," he said.
"I need to hit the ball better, I need to chip better, I need to putt better, and I need to score better," Woods added.
The U.S. beat Europe in the last Ryder Cup match at Valhalla in 2008 without Woods as he was recovering from knee surgery.
He also has an indifferent record in the biennial match with 13 losses in 25 matches in five appearances.
While Woods may miss the Ryder Cup, he confirmed Monday that he will play in the HSBC Championship in Shanghai in November.
It will be Woods' fourth visit to the Sheshan International Golf Club and he is still searching for a victory.
Defending champion Phil Mickelson will also be in the field for the World Golf Championship event.