Justin Thomas and Nicholas Thompson both shot an opening-round 63 to earn a share of the lead after day one of the John Deere Classic in Illinois.
The American duo enjoyed birdie-laden first rounds to finish Thursday's session on eight-under-par - one stroke clear of the pack.
Charles Howell III and Luke Guthrie are among those in pursuit as the pair sit one shot back.
Further back, Steve Stricker is one of five players on six-under, along with Daniel Summerhays, Shawn Stefani, Steven Alker and Robert Garrigus.