Silvis - Americans Zach Johnson and Brian Harman and South Africa's Rory Sabbatini each fired eight-under-par 63s to share the lead after Thursday's first round of the $4.7 million John Deere Classic.
Sabbatini and Johnson enjoyed bogey-free tours of the TPC Deere Run while Harman suffered one bogey as all three finished 18 holes one stroke in front of Americans William McGirt and Todd Hamilton, the 2004 British Open champion playing his first PGA round of the year, and Australian Steven Bowditch.
Johnson, ranked 16th and set for next week's British Open at Hoylake, began on the back nine and birdied six of his first eight holes and eight of his first 11 in the lowest round of his 12 appearances at the event, only a 90-minute drive from his hometown.
A 19-foot birdie putt at the par-3 12th was the longest that Johnson needed in the round thanks to sharp iron play and solid work off the tee on a course where he won in 2012 and lost in a playoff last year to then-teen Jordan Spieth.
Johnson enjoyed seven top-10 showings after his runner-up effort last year, including a win in the US PGA playoffs at the BMW Championship.
"I have found myself a little impatient in the weeks prior to this," Johnson said. "In the US Open, I made the cut, but it was pretty boring, bad golf after that. I was a little spent."
After a two-week break, Johnson was back on form in Silvis, Illinois and pondered the tour record score of 59 with six holes remaining.
"It entered my mind very briefly," he said. "I don't want to say I should have shot 61 or 58 or 60 or 59 or whatever. But I had a chance."
Sabbatini ran off runs of three birdies in a row on the front and back nines in his round, sinking a 17-foot birdie putt at the third and a 22-foot birdie putt at the fourth to finish his first such streak.
He sank another 17-footer at the par-3 seventh and another 22-footer for birdie at 12, then ran off three more in a row from the 15th to the par-5 17th to grab his share of the lead.
Harman birdied the third, fifth and ninth holes, then ran off four birdies in a row starting at the 11th and highlighted by a 22-foot birdie putt at the 12th and a 15-footer at 13.
After finding the rough off the tee at 15 on the way to his lone bogey, Harman put his tee shot at the par-3 16th two feet from the cup for a tap-in birdie and sank a seven-foot birdie putt at the par-5 17th.Scores on Thursday after the first round of the $4.7 million John Deere Classic (par 71, USA unless noted):
63 - Zach Johnson, Rory Sabbatini (RSA), Brian Harman
64 - Todd Hamilton, Steven Bowditch (AUS), William McGirt
65 - Brendon de Jonge (ZIM), Kevin Tway, David Toms, Robert Streb
66 - Charles Howell, Ryan Moore, Johnson Wagner, Jerry Kelly, Justin Hicks, Trevor Immelman (RSA)
67 - Harris English, Bo Van Pelt, Nicholas Thompson, Bud Cauley, Wes Roach, Scott Brown, Sean O'Hair
- Brice Garnett, Kevin Na, John Senden (AUS), JJ Henry, Kevin Kisner,
Alex Prugh, Ricky Barnes, Troy Merritt, Steve Stricker, John Huh, Brian
Stuard, Kevin Chappell