Pace shook off the angler who tied him for the lead Friday, Michael Iaconelli of Pittsgrove, N.J.
Idaho's Brandon Palanuk was in second place with 36-4, Iaconelli was in third with 35-3, North Carolina's Hank Cherry was in fourth with 31-12 and Oklahoma's Jason Christie was in fifth with 31-5.
Greg Hackney of Gonzales goes into the final day of competition in 15th place with 27-5.
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With a Saturday catch that weighed 21 pounds, 12 ounces, Pace racked up 43-4 over two days of competition on Grand Lake O' the Cherokees. His second-day weight was 4 ounces more than the 21-8 he brought to the scales Friday.
"I didn't fish differently today at all," Pace said. "For me, it's been all about committing to the way I can catch the big ones. I took a big, big risk to do that."
He said Saturday started slowly for him, with his first bass coming about 10 a.m. He ended up catching the day's largest bass, a 7-pound, 2-ounce largemouth.
"I think I'm doing something that has potential, and will hold through tomorrow," he said, playing it close to the vest.
Pace, who competes in the sport's premier circuit, the Bassmaster Elite Series, has never won a Classic. He came close in 2008 on Lake Hartwell, when he was second to Alton Jones of Texas.
Brandon Palaniuk of Rathdrum, Idaho, was the angler left hanging 7 pounds behind the leader, even though he made a charge by catching 3 pounds more Saturday than he did on Friday. The 25-year-old pro's two-day total of 36-4 jumped him from 11th place into the runner-up spot on Saturday going into Sunday's final round.
"I caught seven yesterday, seven today," Palaniuk said. "I just happened to get a couple bigger bites today. It was actually my last fish that made the big difference."
Iaconelli dropped from a tie with Pace for first into third place with a 35-3 total. In fourth place was Classic rookie Hank Cherry from Maiden, N.C., with 31-12. Fifth with 31-5 was local favorite Jason Christie of Park Hill, Okla.
Four-time Classic champ Kevin VanDam of Kalamazoo, Mich., had an uncharacteristic day: He brought in only four bass. One fish shy of a limit, he fell from fourth place to sixth with his two-day total of 30-14.
If Pace's Carhartt Big Bass of the day of 7-2 holds through Sunday as the heaviest fish brought to the scales over three days of Classic competition, he could collect a $2,500 bonus from Carhartt.
The top 25 anglers will return Sunday to Grand Lake for the final day of competition. They'll launch at Wolf Creek Park in Grove, Okla., at 7 a.m. CT.