Hudson Swafford has opened up a one-shot lead at the halfway stage of the CareerBuilder Challenge.
The world number 204 hit seven birdies during a second successive round of 65 to hold a narrow advantage over Dominic Bozzelli and Danny Lee.
British representatives Greg Owen and Martin Laird are in a share of sixth place alongside Phil Mickelson, while Paul Casey is six shots off the lead in 13th spot.
A 66 from Jason Dufner has moved him towards the top 20, while former leading amateur Jon Rahm and Ireland's Seamus Power are also in contention at the halfway stage.
Top American players Patrick Reed and Zach Johnson are currently down in 49th position.
