Argentina's Anders Romero fired his second consecutive seven-under par 65 on Friday to grab a one-stroke lead after the second round of the $3.5 million US PGA Tour Puerto Rico Open.
Romero, whose only PGA title came in 2008 at New Orleans, was on 14-under 130 after 36 holes, one shot ahead of American Scott Brown with US rivals Peter Uihlein and Steve LeBrun on 132 and Argentina's Fabian Gomez fifth on 133.
With 65 of the tour's top players at the World Golf Championships event at Doral in Miami this week, the Puerto Rico event offers a title chance to some of the PGA's unheralded standouts.
Romero, who shared the lead with Australian Cameron Percy when the day began, birdied the par-5 second, par-4 third and par-5 fifth holes but a double bogey at the par-3 eighth sent him tumbling back down the leaderboard.
The 31-year-old South American responded with starting the back nine with back-to-back birdies, added another at 13, then had back-to-back birdies at the par-5 15th and par-3 16th before closing with a birdie at the par-5 18th.
Brown birdied three of the last four holes after a bogey at 14 to fire a 63 and move into second place. He birdied the second and fifth, then eagled the par-4 seventh before starting a run of three birdies in a row at the eighth.
Percy fired a 70 to stand five strokes off the pace.