Former champion Ben Crenshaw shot a five-under-par 65 Friday to take the second-round lead in the $750,000 Byron Nelson golf tournament at Irving, Tex.
The round was marked by the on-course withdrawal of Arnold Palmer, due to pain in his ribs.
Crenshaw, who won the 1983 Nelson after it moved to the Tournament Players Course from Preston Trail, had a six-birdie, one-bogey round in the 90-degree heat for a 36-hole total of 131.
He held a two-stroke edge over Jeff Sluman, who shot a 67, and Mark Wiebe, who had a 69. Three shots back were Craig Stadler, who shot a 66, and John Cook, who had the day's best round, a 64.
Palmer, 58, who shot a 70 in the opening round, said, "I had a catch in my rib cage when the day began. It just kept nagging me and got worse."
Palmer received medication at the sixth hole but couldn't swing properly and double-bogeyed the 10th after playing the front nine in one-over-par 36.
"It hit me on my swing on No. 11," said Palmer, who knocked his tee shot in the water. "It was a shame I had to leave. I was crushing the ball. But my ribs were killing me."
Nancy Lopez, looking to regain the No. 1 spot on the LPGA Tour, shot a four-under-par 68 to share the first-round lead in the $250,000 Chrysler-Plymouth tournament at Middletown, N.J.
Lopez had five birdies and a bogey on the 6,232-yard Navesink Country Club course and was tied with Alice Ritzman, who is looking for her first victory in 10 years on the tour. Ritzman had four birdies and no bogeys in a round that included three long birdie putts.
Janet Coles was third at 69.
Defending champion Ayako Okamoto of Japan withdrew after nine holes because of neck pain.
Quinton Gray, winless in five years on the PGA Seniors Tour, shot a three-under-par 67 to take the lead in the first round of the $225,000 United Hospitals tournament at Chester Valley Golf Club in Malvern, Pa.
Gray, who made the tournament field as an alternate, was two strokes in front of Dick Ryhan, Bobby Nichols and Bruce Devlin.
Lou Graham, Bill Collins, Billy Casper and Lee Elder each had a 70.
Gray, who played in two previous senior events this season, finishing in a tie for 49th and 20th, had 10 top-10 finishes last year.
Richard Boxall had seven birdies in a nine-hole stretch while shooting a six-under-par 64 for a 36-hole total of 127 and a four-stroke lead over fellow Briton Mark James, who had a 68, after two rounds of the $330,000 Spanish Open at Santander, Spain.
Spaniard Severiano Ballesteros, the heavy favorite playing on his home course, managed a 67 for a 139.