Bryson DeChambeau is in a three-way tie for the lead as the second round of the Puerto Rico Open was suspended due to darkness.
DeChambeau, the low amateur at the 2016 Masters, carded a seven-under 65 in his second round in Rio Grande on Friday.
He is at 11 under alongside fellow Americans D.A. Points (69) and Bill Lunde, who was through 15 holes when darkness stopped play.
A congested leaderboard sees six players - Chris Stroud, Tim Wilkinson, J.J. Henry, Tom Hoge, Rafael Campos and J.J. Spaun - sitting tied for fourth at 10 under.
Wilkinson produced the round of the day, making five straight birdies from the fourth to the eighth, having eagled the second.
German Alex Cejka, the champion in 2015, is in contention as one of seven players at nine under.
Graeme McDowell, K.J. Choi and Ian Poulter are well off the pace at two under.