Jason Dufner held a two-shot lead after shooting a bogey-free 5-under 66 in the second round of the Transitions Championship.
Dufner started the round with three birdies in his first five holes and kept that momentum all the way through his round on the way to a 10-under total, two ahead of Padraig Harrington.
Luke Donald, who will regain the world No 1 ranking if he wins the Transitions Championship, one of five players three shots off the lead.
Spanish livewire Sergio Garcia is also in a good position going into the weekend rounds, four shots back.
Some of the bigger names to miss the cut were Japan's Ryo Ishikawa, Colombian Camilo Villegas and Masters champion South African Charl Schwartzel.
South African performance
Ernie Els and Retief Goosen are neck-and-neck in a tie for 13th on 5-under, Rory Sabbatini is three shots behind them on two under, while Brendon de Jonge and Tim Clark, like Schwartzel, missed the cut.