Seamus Power carded an impressive opening round 66 to break into the top 20 but five-time major champion Brooks Koepka caught the eye at the CJ Cup Byron Nelson in Texas.
Koepka's gradual return to form in 2026 continued as he registered six birdies and an eagle to card an eight under par 63, the same score as Jesper Svensson, at TPC Craig Ranch.
This was good enough to give him the outright lead until late on day one before Taylor Moore went one better.
Two-time PGA Tour winner Power is four strokes off the leaders after a strong opening round, the Waterford golfer notching six birdies, with just one dropped stroke on the par-3 fourth hole - his 13th of the day.
Si Woo Kim and Stephen Jaeger are among a number of players currently in tied-fourth on seven under.
Power is in illustrious company among the large cohort on five under, with world number one Scottie Scheffler also posting a round of 66 on Thursday, with five birdies and no dropped strokes.
Tony Finau, Chris Kirk and Sungjae Im are among the sizable group of players on four under.
