Russ Cochran shot a 5-under 67 on Saturday in the SAS Championship to increase his lead to four strokes, the largest 36-hole margin the history of the Champions Tour's event.
"I don't have any experience with a four-shot lead so I don't know what to expect," Cochran said. "I'm sure I'll have to be on my toes."
Cochran, the 51-year-old left-hander coming off his first victory on the 50-and-over tour two weeks ago in South Korea, birdied the final two holes at Prestonwood Country Club to finish at 13 under.
Ted Schulz (68) was second, and defending champion Tom Pernice Jr. (71) was 8 under along with John Cook (64) and Nick Price (69).
"I played pretty solid today," said Schulz, the winner at Pebble Beach this month. "I probably could have putted just a little better."
Cook played the back nine in a tournament-record 8-under 27, eagling the par-4 14th and par-5 17th.
"Yesterday, I just didn't do anything very well," said Cook, who spent time on the range after his first- round 72. "I must have found something that worked today."
After his record-setting nine holes, Cook, who started on No. 10, played even par on Prestonwood's front nine.
"The front side is just a hard nine holes of golf, and you kind of have to survive the front," Cook said. "But I battled back. I didn't want to let a really good round of golf go by the wayside."
Cochran also said the front nine is the harder of the two nines.
"The first part of the golf course is unbelievably difficult," said Cochran, who will be paired with Cook and Schulz in the final group. "The first several holes are pretty demanding, and it keeps you off-balance."
Keith Fergus had a double-eagle 2 on the 17th, holing a 3-iron shot from 210 yards. He finished with a 64, leaving him eight strokes back at 5 under. Schwab Cup points leaders Bernhard Langer and Fred Couples also were 5 under after 68s.