Danny Lee continued his momentum from his second-placed finish in Puerto Rico with a first round of 68 to share the lead at the Valspar Championship.
Lee's 19-under-par total at the Puerto Rico Open was bettered only by Chesson Hadley at 21 under, and he was in similar form at the Innisbrook Resort in Palm Harbor, Florida.
The Korean-born New Zealander started on the back nine and made two birdies in his first three holes, with another at the 15th seeing him to the turn in 32.
He birdied the first but bogeyed the sixth in a level-par second half and was joined at three under par by Americans Matt Every and Pat Perez and Australia's Greg Chalmers, who each had five birdies and two bogeys in their rounds.
"I gained a lot of confidence after last week playing with the finish in Puerto Rico," Lee said.
"It really helped me a lot with that confidence stuff, and I'm hitting it really well right now. My ball striking is the best it's ever been, especially with the putting."
A large group at two under included Belgian Ryder Cup star Nicolas Colsaerts alongside Americans Bill Haas, Robert Garrigus, Tommy Gainey, Michael Putnam and James Hahn.
Italy's Matteo Manassero, playing in the final group, joined them after he bounced back from a bogey at the 17th by holing a superb 40-foot birdie putt at the last.
Scotland's Russell Knox led the British challenge at one under, with Englishmen Luke Donald and Justin Rose carding level-par 71s along with Darren Clarke of Northern Ireland.
Paul Casey and David Lynn were a further shot back, where they were joined by some big names including major winners Jason Dufner, Ernie Els, Webb Simpson, Retief Goosen, Angel Cabrera and Mike Weir.
Brandt Snedeker and rising star Jordan Spieth were also at level par, but Hadley bounced back down to earth with a disappointing four-over-par 75 featuring four bogeys and a double.