Cameron Smith in contention at PGA Championship

Cameron Smith remains firmly in the hunt for PGA Championship glory after surging to within one shot of the lead midway through his final round in Pennsylvania.

After starting the day four strokes behind American third-round leader Alex Smalley, Smith picked up three birdies on his front nine to climb to 5-under for the championship.

He was initially behind only Matti Schmid, but the German slipped back to join the 5-under crowd, shortly after Englishman Aaron Rai moved to 6-under.

That came after three bogeys on the front nine for Rai, but he eagled the ninth and birdied the 11th to take the lead.

Smith's charge could have been even better, with Australia's resurgent former world number two lamenting a cruel lip-out on the fifth hole and then cursing himself for leaving short an eagle attempt on the par-five ninth.

He also clipped the lip with a tricky birdie putt on the par-three 14th before hooking his 15th tee shot into the thick stuff on the following hole.

Smith hacked across the fairway into a greenside bunker, but managed to get up and down to save par.

Another par followed on the only par five of the back nine, before a late stumble by the Australian on 17.

He sent his tee shot wide right on the par three and left his long putt well short. He missed the follow-up and had to tap in for his first bogey of the round and first three-putt of the tournament.

Still, Smith was right in the mix after evoking memories of his unforgettable 2022 British Open comeback triumph at St Andrews in 2022.

At 5-under, Smith was level with two-time champion Justin Thomas, who captured the clubhouse lead with a sizzling final-round 5-under 65 at Aronimink Golf Club, outside Philadelphia.

Thomas equalled the PGA Championship record to win from seven strokes back at Southern Hills in 2022 and found himself facing a similar deficit after taking bogey on the third hole on Sunday.

But the American former world number one peeled off six birdies in 12 holes before draining a lengthy par putt on the last to keep alive his hopes of etching his name on the Wanamaker Trophy for a third time.

The unfancied Smalley, winless in 140 PGA Tour starts, maintained his lead early with three pars to start his final round before dropping back into the chasing pack with a double bogey on six.