Shawn Stefani fired a 6-under 65 on Thursday to grab a 2-stroke lead after the opening round of the Tampa Bay Championship.
Stefani, a tour rookie, is coming off a tie for 39th at the Puerto Rico Open last week. That was his best finish of the season.
Brian Harman tripped to a bogey at the last for a 4-under 67 on the Copperhead Course at Innisbrook Resort and Golf Club.
Harris English stumbled to a double-bogey at the 18th. That dropped him to minus-3. He was joined there by Tag Ridings, Peter Tomasulo and Brendan Steele.
Two-time champion K.J. Choi and 2004 winner Vijay Singh both carded 2-under 69s. They stand alongside Geoff Ogilvy, Dicky Pride, Lucas Glover, Chez Reavie and Roberto Castro.
Stefani, who has made the cut in three of his six tour starts this year, started on the back nine and stuffed his second shot inside two feet at his opening hole. He made it two in a row at the 11th as he chipped his third to within four feet.
The 31-year-old missed the green at the par-5 14th, but chipped to two feet and kicked that in for his third birdie. Stefani parred the final four holes of his opening nine.
Stefani dumped his second into a bunker at the par-5 first. He blasted to 13 feet and drained the birdie putt to move to minus-4. At the third, he left himself 22 feet for birdie and rolled that in for his fifth birdie.
The two-time winner on the Web.com Tour last year grabbed the lead at 6-under with a tap-in birdie at the par-5 fifth. Like his opening nine, Stefani parred the final four holes to end at 6-under.
"I wasn't really starting the day with a lot expectations," Stefani stated. "Just want to go out and have fun and hit some good shots."
Harman, who tied for 18th in Puerto Rico last week, parred his first three holes before converting an 11-foot birdie try at the 13th. After five straight pars, he sank a 10-footer for birdie on No. 1.
The former Walker Cupper caught fire after three consecutive pars. Harman birdied the fourth from off the green to get to 3-under.
Harman again rolled in a birdie try from off the green at the sixth. His 11- foot birdie putt at the seventh was his third straight birdie. However, Harman bogey at the ninth to end two back.
"I stayed real patient today. Never pushed when I really wanted to," said Harman. "I drove it well and stayed in play. When I hit it out of play, I just hit it up there in front and tried to make par."
NOTES: Defending champion Luke Donald carded a 1-under 70 and is one of 12 players tied for 14th along with Nick Watney, Jason Day and Patrick Cantlay among others ... There are five other former winners in the field with Gary Woodland (71) being closest to the lead as he shares 26th ... World No. 6 Louis Oosthuizen, the second highest ranked player in the field behind Donald, struggled to a 2-over 73 and is tied for 70th.