With little breeze and attack-ready pin positions, some of the game’s premier talents seemingly arrived at the Philadelphia track with a spring in their step.

And, teeing off nearly four hours before the final group, Northern Ireland’s McIlroy seized an opportunity to give the later starters something to ponder.

Starting at one over – five back of overnight leaders Smalley and Maverick McNealy – the back-to-back Masters champion hauled himself into a share of the lead at four under with six birdies in his opening 13 holes.

He said his plan had been to get to five under “to make the leaders shoot under par to be ahead of me”.

And while he stumbled over the closing holes with a bogey at the 17th, he still has a realistic shot at becoming only the sixth man to win the first two majors of the year.

“I’ve climbed my way out of that hole,” he said. “I’m proud of myself for doing that, but there’s one more day left, and I feel like I’ve still got a good chance.”

Having been outside the top 100 after Thursday’s opening round, a McIlroy win would mark the greatest major championship comeback after 18 holes.

Steve Jones, who won the 1996 US Open after being tied 84th at the end of the first round, currently holds that record.

Two of McIlroy’s Ryder Cup team-mates also entered the fray. Thirteen years removed from his US Open win at Merion – just six miles from Aronimink – Rose has suffered recent heartache in majors.

He lost last year’s Masters in a play-off to McIlroy and led this year’s tournament with nine holes to play before faltering down the stretch.

However, in his lowest round with his new McLaren irons, the 45-year-old carded six birdies and a bogey to sit four back.

Rahm is another European star chasing redemption. The Spaniard has not added to his two majors since joining LIV Golf before the 2024 season and chased down Scheffler at Quail Hollow last year before imploding over the final holes.

The 31-year-old – hoping to become Spain’s first US PGA winner – missed a four-footer to drop a shot on the final hole but will still be widely regarded as the man to beat.

“As hard as it is to play, the challenge can also be kind of fun if you do well,” he said.

“That’s probably the reason why the leaderboard is so bunched up and it’s going to be such a good Sunday.”

McIlroy will play alongside 2024 US PGA and Open champion Xander Schauffele in a group that is likely to draw huge crowds, while a pair of Masters winners also have the pedigree to succeed.

Patrick Reed, who won the Green Jacket in 2018 is also at three under, while 2021 victor Hideki Matsuyama is a shot further adrift.