McIroy, who entered the week as the No. 5 seed, is one shot behind leader Brooks Koepka. Casey, who started the tournament as the No. 16 seed, is alone in fifth place and four strokes out of first.
The two players were able to go low Friday, despite some aggressive hole locations that made scoring more difficult. McIlroy made his lone bogey on the first hole and added four birdies, including the final two holes. Casey had five birdies and two bogeys scattered throughout his card.
“If you don’t hit fairways, with this Bermuda rough, you have no control of your golf ball,” McIlroy said “You’re sort of guessing whether it’s going to fly or come out soft. So, you need your scrambling boots on this week and I scrambled well.”
McIlroy has been here before; the Northern Irishman won the 2016 FedEx Cup. He’s had a remarkably consistent season with two wins (The Players Championship and Canadian Open) and a Tour-best 13 top-10s in 18 starts.
Casey has been in contention at East Lake in each of his previous five appearances, which includes four top-5s. His worst was a tie for 11th last year. The Englishman has had a successful season on the PGA Tour, collecting his third career victory with a defense of his title at the Valspar Championship.
Casey might be one shot closer had he grabbed the proper club on the final hole. He received the yardage for the approach – he wanted to land it 234 yards for the flag at 248 – and launched a beauty, only to see it take one hop and land behind the green.
“Then I look down and realized I hit the 3-iron, not the 4-iron,” Casey said. “Because, you know, we’re not playing for much this week and it’s not important.”
Casey pulled the club himself, so he couldn’t blame the caddie. The heads on the 3- and 4-irons are identical, with one bent stronger than the other.
“Clearly I can’t tell the difference when I put them down,” he said. “One’s got a little ‘4’ on it and the 3’s got nothing on it. The sad thing is, it’s the second time I’ve done it this year.”