Colombian Sebastian Munoz and American Chesson Hadley are joint leaders after the opening day of the John Deere Classic in Illinois on Thursday.
Munoz, ranked 75th in the world, hit 17 of 18 greens in his eight-under round which included nine birdies, including five in a row to finish the day.
Hadley, who blew a four-shot lead heading into the final round at the Palmetto Championship three weeks ago, carded an eight-under-63 with eight birdies at the TPC Deere Run.
Hank Lebioda bogeyed on the final hole of the day to let slip a share of the opening day lead.
Lebioda is tied with Chez Reavie and Camilo Villegas at seven under after, marginally ahead of Ryan Moore who carded a six-under-65.
Last week's Rocket Mortgage Classic winner Cameron Davis is four strokes behind the leaders and in contention, landing an eagle on the second hole.
Kevin Na is also four under, with reigning champion Dylan Fritelli carding a three-under 68.
World number 16 Daniel Berger made a 45 foot putt on the ninth hole but finished two under.