Alex Cejka took the midway lead at the Puerto Rico Open on Friday, the German one shot clear in his bid to win a maiden PGA Tour title.
The German, who resides in Las Vegas, posted a five-under 67 at Trump International Golf Club in Rio Grande, finishing strongly with three late birdies.
After starting his round on the 10th, Cejka turned at two under, and picked up more strokes on the fifth, seventh and ninth to claim the outright lead after a bogey-free day.
In just his third career PGA Tour start, American Brandon Hagy sits outright second (67) on six under, one ahead of Argentinean Emiliano Grillo (70).
Seven players, including defending champion Chesson Hadley, are tied for fourth at three under.
Last season's PGA Tour rookie of the year, Hadley (70) shot two under for the day, along with Brendon de Jonge, while each of Jonathan Byrd, Scott Pinckney, Jon Curran and Rod Pampling have gone 70-71 heading to the weekend.
Glen Day was the only of the group tied for fourth to break 70 on Friday, as he carded a 68 to improve five strokes on his opening round.
John Daly (70) is among those tied for 11th at two under, along with nine other Americans plus Spaniard Gonzalo Fernandez-Castano (69).
Overnight leader Mark Hubbard is among the group, after shooting a two-over 74.