US PGA: Tiger Woods trails leaders by nine after opening 74

Woods was an injury doubt ahead of the year's final major

Tiger Woods carded a three-over-par 74 in the first round of the US PGA Championship at Valhalla, leaving him nine shots behind the leaders.

Woods, 38, was a doubt for the final major of the year, having injured his back on the final day of last week's WGC-Bridgestone Invitational.

He made four bogeys and one birdie on Thursday and could miss Friday's cut.

"It wasn't very good," said four-time winner Woods, who is hunting his 15th major title in Louisville, Kentucky.

"My swing was dialled in on the range. Unfortunately, I didn't carry it to the golf course.

"My back's a little bit stiff, but that's about it. I'm going to get treatment and make sure this thing is nice and loose for Friday."If I get under par for two rounds, that will be right in the ball game."

Woods's last major title was the US Open in 2008 and an injury-plagued season means he will be relying on a captain's pick for next month's Ryder Cup.

The automatic qualification period for the Ryder Cup at Gleneagles ends after the current tournament, with players looking to secure their place on the USA and Europe teams.

Woods, who made his Ryder Cup debut in 1997, was 69th in the American standings before the US PGA, with only the top nine players qualifying automatically for Tom Watson's team.

Unless he plays and wins next week's Wyndham Championship, Woods will miss the FedExCup Playoffs, meaning he will play no more competitive golf before Watson announces his three wildcards on 3 September.