Rickie Fowler, Shane Lowry and defending champion Justin Thomas surged into contention on the resumption of a weather-affected second round at Bellerive.
Gary Woodland holds a halfway one-shot lead, at 10 under for the championship, over Kevin Kisner as half of the field were forced to return for 7am local time on Saturday morning after storms forced an early postponement to the second round.
World No 9 Fowler, chasing his first major title, completed a three-under-par 67 to join compatriot Brooks Koepka at the eight-under mark, while Lowry sits at seven-under after compiling a flawless six-under 64 with Thomas a shot further back.
The adverse weather was replaced with sunshine and clear skies as 78 players, including the marquee grouping of Tiger Woods, Rory McIlroy and Thomas, resumed play amid soggy conditions with all three making ground up the leaderboard.
Fowler had made a strong charge up the leaderboard on Friday before play was suspended and a birdie at the short par four 11th saw him move within four shots of Woodland’s lead.
A bogey at the par three 13th, after finding the bunker with his tee shot, saw him fall back to his overnight score of seven-under but a further birdie at the 17th moved him within two at the midway stage.
The biggest move by a European was from Lowry as the Irishman finished with a birdie at the ninth – his final hole – to sit at seven-under having posted a blemish-free six-under 66.
Lowry, whose best major finish was tied second at the US Open in 2016, holed a 24ft putt for birdie at the par-three third to get to five-under before two gains over the closing three holes put the polish on his round.
Obviously things haven’t been going well for me this year. The last few weeks have been good. I have my brother on the bag, and he’s doing a great job, really enjoyed it, said Lowry, who had restarted on four-under.
And now we’re going out on a Saturday afternoon in the mix at the PGA, it’s great. I have my dad here to watch. Look, it doesn’t get much better.
Thomas, seeking to join Woods as the only other back-to-back PGA champion, picked up four shots as the 25-year-old mixed five birdies with a solitary birdie over the 11 holes he had to complete to move within four shots of the lead.
After opening his day with a gain at the par-five eighth he dropped back to two-under with an immediate bogey at the next but a flawless back nine, including a late birdie at the par-five 17th moved him into contention.
Woods, who had begun his second round at level par, continued from where he left off on Friday as a birdie – his fourth of the round – on his resumption moved him to four-under overall but his back nine was a battle.
The four-time champion missed five-foot putts for par at the 10th and 12th but in between made birdie at the short par-four 11th and a tap-in birdie at the 17th saw him sit six shots adrift.
I just have to make birdies, Woods said of his mindset going into the third round. This golf course is stacked right now and everyone is bunched.
And on top of that, if you hit the ball well enough, then you’re going to leave yourself in the right sections. And there’s not a single putt out here that you’re afraid of that it’s going to get away from you.
The only thing is you have to hit, a couple putts, you got to hit harder than normal, and there might be a few little spike marks. But you can take a lot of the breakout and be very aggressive.
That’s one of the reasons guys are making birdies from everywhere.
McIlroy also resumed with a birdie at the par-five eighth and the Northern Irishman picked up two further gains, including a 58-foot chip in at the 14th, to move to three-under and well inside the cut mark of level par.
Sergio Garcia, who missed the cut for the fifth successive major, Masters champion Patrick Reed and Phil Mickelson were among the notable names to miss out on progressing to the final two rounds.
Mickelson’s second round one-over 71 means the American will miss out on automatic qualification for the Ryder Cup for the first time since 1993.