Tiger Woods conceded he was running out of time to win major titles after falling out of contention at the US PGA Championship on Saturday.

The 44-year-old American shot a two-over 72 for the second successive round to leave him with little to play for leading into the final day at TPC Harding Park in San Francisco.

It will end as another opportunity missed for the reigning Masters champion in his bid to equal Jack Nicklaus' record of 18 major victories.

Woods has managed 15 over a 24-year professional career, but only one since 2008.

"There's not as many [opportunities to win] as when I first started playing," Woods said after completing his round.

"The reality is that the golf courses are getting bigger. They are getting longer. The margin between making the cut and the lead is a lot smaller than it used to be. Used to be sometimes 12 to 15 shots.

"Now we had, what, nine shots here? It's just different. It's getting tighter and it's getting harder to win events, but you look at the leaderboard of most major championships, you see the same guys.

“May not be always the same winners, but you see the same handful of guys are there.

“They understand how to win major championships, how to win the big events, how to plod their way along, how difficult it is to win these big events."

Putting again proved a problem for Woods as he failed to make a birdie until the 16th hole.

Though well behind the contenders, Woods said he had a clear goal in mind for the final round.

"You just keep fighting, no matter what," he said. "Whether the rounds are shooting 61s or shooting 81s, the intensity should always be there, the effort should always be there.

"I keep fighting until the end [with] pride in what I do. I love to compete. Unfortunately I didn't do my job today.

"At the end it clicked and hopefully I can get something going tomorrow and get into the red for the tournament."