ST. LOUIS — Tiger Woods’ PGA Championship week looked like it was getting shorter by the moment early in Thursday’s opening round at Bellerive.

Woods, with a bogey on his first hole, No. 10, and a double on No. 11, staggered to the 12th tee at 3-over par through his first two holes, and the cutline — whatever it turns out to be — must have felt miles away.

But Woods, playing in all four major championships for the first time since 2015, characteristically fought his way back to an even-par 70 by the time he was finished to somehow stay in contention — six shots off the lead held by Gary Woodland at 6-under par.

“I was able to grind out a score today,’’ Woods said. “I just hung in there. I was trying to grind away at it, pick away at it, and trying to get to maybe 1-over par at the turn. I was hitting the ball all right. If I could somehow get myself in the right sections [on the greens], I could hole a few putts.’’

Woods surely saved his round, and might have saved his tournament, on No. 15, where he somehow saved par from the woods.

“It kept me in the golf tournament,’’ Woods said. “I could have easily gone the other way, being 3-over through two. A lot of things could happen. Not a lot of them were positive, but I hung in there and turned it around. Just happy to be within five right now.’’

Woods, who looked at times like he was laboring in the muggy, 90-degree heat, changing his shirt during the round, said, “The main thing about major championships is, make sure you have enough energy. This is a long run. These are marathons. These are four long days. They’re slow rounds.’’

Woods played with defending champion Justin Thomas, who shot 69, and two-time PGA champion Rory McIlroy, who shot 70.

The 70 Woods rallied to post actually was his lowest opening-round score in a PGA Championship since 2012.