Tommy Gainey and Camilo Villegas were in fine form on the opening day of the Children's Miracle Network Hospitals Classic at Lake Buena Vista.
Gainey went into a share of the lead after striking six birdies, an eagle and a bogey in his seven-under-par round at the Magnolia course in Florida.
Colombian Villegas joined him after also hitting an excellent 65, which contained eight birdies and a dropped shot at the par-four 10th.
Charlie Wi could be on course to overtake the pair after going in at the turn just one stroke behind.
The Korean eagled the par-five seventh to go with his four birdies in a so far unblemished round.
Former two-time Ryder Cup representative Henrik Stenson was among a cluster of players on four under, while 2009 Open winner Stewart Cink was a shot further adrift.
