Steve Wheatcroft holds a one-shot lead going into the second day of the John Deere Classic after going round nine-under on Thursday.
Wheatcroft's blemish-free round of 62 saw him ride home on a streak of six birdies, sealing a career-low.
The American is just ahead of countryman Michael Kim, while a four-strong chasing pack of Johnson Wagner, Nick Taylor, Andres Romero and Joel Dahmen are tied for third after finishing two shots off the pace.
Ireland's Seamus Power finished six shots off the lead in Illinois to tie in 37th, while Englishman Brian Davis carded 69 to tie 56th.
Francesco Molinari, who won the Quicken Loans National a fortnight ago was tied seventh after going round in 65.