Darren Clarke shot a seven-under-par 63 to put himself in contention at the Sanford International at Minnehaha Country Club.
Clarke, a past winner of this event, combined eight birdies with a solitary bogey to sit one shot off the lead in South Dakota.
Charles Schwab Cup leader Steve Stricker and 2021 Sanford International runner-up K.J. Choi share the first-round lead after matching the course record with a pair of 62s.
Stricker, a former two-time winner of this event, made five birdies in a row to start the back nine, matching his second-lowest 18-hole score on PGA TOUR Champions. Stricker, who is seeking his 17th win on the PGA Tour Champions, is joined by KJ Choi on eight-under-par.
Choi, looking for his second win on the Champions tour made eight birdies and a bogey on route to his third first round co-lead of his Champions tour career.
Clarke is joined by Alex Cejka, David Toms and Rocco Mediate on seven-under-par, one shot back. 2019 champion Rocco Mediate birdied seven of his last 10 holes en route to his 63.
There were two holes in one made in the opening round in South Dakota. Fred Funk made a hole-in-one on the 17th hole with a hybrid from 199 yards and John Senden made a hole-in-one on the 8th hole with a pitching wedge from 132 yards.
Clarke gets his second round underway alongside David Toms and Rocco Mediate at 12.06pm local time, 6.06pm Irish time.