Luke Donald's bid to defend his Tampa Bay Championship crown in Florida suffered a setback after a costly finish to his opening round.
Donald, an early starter from the 10th tee, had hit the front on four-under par after birdies at the 13th, 14th, 1st and 5th but bogeyed three of his last four holes to slip back into the pack and five behind surprise leader Shawn Stefani, who leads by two after a six-under par 65.
"I'm extremely disappointed right now," Donald said after signing for a one-under 70. "I had it really under control and could have been six or seven-under with a couple of putts. Obviously to finish like that, it leaves a bitter taste in my mouth."
However, with scoring tough on the par 71 Copperhead Course at Innisbrook, he ended the day in a tie for 14th.
The world number three wasn't the only player to hit the front and suffer a late mishap.
Harris English, who started in the afternoon wave, topped the leaderboard after racing to five-under par after 11 holes but he found a greenside bunker at the 18th and three-putted for an ugly double-bogey to slip back to three-under.
Fellow American Brian Harman had also hit five-under but bogeyed his final hole, the ninth while, continuing the theme of late mishaps, recent WGC-Accenture Matchplay champion Matt Kuchar double bogeyed two of the last three holes to slump from three-under to one-over.
Harman is still solo second though while English is tied for third on three-under alongside compatriots Tag Ridings and Brendan Steele.
Leader Stefani has missed three of his six cuts on the PGA Tour this year, with a best of tied 39th in Puerto Rico last week. However, the rookie did win twice on the Web.com Tour in the second half of 2012, one of those triumphs coming in Florida - the Miccosukee Championship in October.
His bogey-free 65 included birdies at each of the four par fives and further gains at the par four third and 10th.
The pack at two-under in tied sixth features major winners Vijay Singh, Geoff Ogilvy and Lucas Glover along with two-time champion here KJ Choi.