Andres Romero birdied his last four holes to take the second-round lead in the Reno-Tahoe Open with 22 points in the modified Stableford scoring format on the edge of the Sierra.
The Argentine player who finished third last year had nine birdies, a bogey and a double bogey on Friday for a one-point lead over Gary Woodland.
The scoring system awards eight points for double eagle, five points for eagle, two for birdie, zero for par, minus-one for bogey and minus-three for double bogey or worse.
Woodland had a chance to take the lead on his last hole when his 90-yard approach glanced off the pin, but missed a 5-foot birdie attempt.
Stuart Appleby, Rod Pampling and former University of Nevada player Charlie Wi were three points back at 19. David Toms had 17.