South Korea's K.J. Choi shot a 4-under 66 on Saturday and holds a two-shot lead at 11-under 129 after two rounds of the Sanford International at Sioux Falls, S.D.
Paul Stankowski, Germany's Alex Cejka and Australia's Rod Pampling are tied for second after two trips around Minnehaha Country Club.
Stankowski fired a round-best 63, Cejka shot 64 and Pampling recorded a 67. Steve Flesch (65) and Mario Tiziani (67) are tied for fifth at 8 under.
Darren Clarke, who shared the first-round lead with Choi, shot even-par 70 and is four shots off the pace. The Northern Ireland product is in a four-way tie for seventh.
Choi had five birdies and one bogey but was particularly strong on the back nine, when he carded four birdies while posting a 32.
Stankowski registered eight birdies and one bogey in his strong round. He carded seven birdies in an 11-hole stretch before a bogey on the par-3 17th and finished with a birdie on 18.
Cejka had two eagles, four birdies and two bogeys. His eagles came on two par-5s -- Nos. 12 and 16.
Pampling made six birdies and three bogeys. All three of his bogeys came on par-4 holes -- Nos. 7, 11 and 13.
Clarke's round got off to a poor start when he double-bogeyed the first hole. He made birdies on Nos. 3 and 4 but soon bogeyed Nos. 6 and 7 and finished the front nine at 2-over 36.
He lost another shot with a bogey on 10 but steadied himself and made birdies at Nos. 12, 15 and 16.
Tom Byrum (67), Australia's David McKenzie (65) and South African Retief Goosen (68) were tied with Clarke in seventh.
--Field Level Media