Justin Thomas, Nicholas Thompson share lead at John Deere Classic

The American duo are a shot clear of countrymen Charles Howell III and Luke Guthrie (both 64s) after a good Thursday for scoring at the TPC Deere Run in Silvis, Illinois.

Thomas' round included 10 birdies and two bogeys, while Thompson went through with seven birdies, an eagle and a bogey.

Americans dominate the top of the leaderboard at the PGA Tour event, with New Zealander Steven Alker (65) the highest-placed of the rest in a tie for fifth.

Alongside Alker are Robert Garrigus, Daniel Summerhays, Steve Stricker and Shawn Stefani, who all sit at six under.

Stricker is a three-time champion at the tournament, winning three straight starting in 2009.

The American has played just six events this year, and his last victory of any sort came at the Tournament of Champions in 2012.

Stricker had eight birdies and two bogeys, which came on the 17th and 18th holes.

Thomas and Thompson started their rounds on the back nine, and the former was four under halfway through his round.

He had runs of four straight birdies twice, from holes 15 to 18 and five to eight.

Thompson eagled the par-four 14th in his round, as he put himself in a good position for a first ever PGA Tour win.

Spencer Levin, Boo Weekley, Michael Thompson, Robert Streb, Tom Gillis, Will Wilcox, Brian Stuard, Scott Pinckney, Carl Pettersson, Zach Johnson and Tyrone Van Aswegen are tied for 10th at five under.

Defending champion Brian Harman made a solid start, sitting at four under and tied for 21st.