Leishman completed two rounds at 14-under-par 128. His 63 matched the course record first posted by Mark Hensby in 2000 and matched eight other times since, including by Michael Putnam in Friday's second round.
Kyle Thompson entered the day tied for second then carded a 6-under 65. He is alone in second place at 13 under. Brendon Todd shot 5-under 66 and is in third at 12-under-par 130.
With just five events left, players are trying to jump into the top 25 on the money list to earn their PGA TOUR cards for next season. The top-five on the leaderboard all need big weeks. Todd is closest to the top-25 as he is 53rd on the money list, while the other four rank between 68th and 87th.
Leishman, No. 75 on the money list, opened with birdies on the first and third. He moved to nine under with a birdie at the sixth. However, Leishman tripped to a bogey on the par 3 seventh.
The Australian bounced back from that bogey with three consecutive birdies from the eighth at Willow Creek Country Club to move to 11-under.
After a par on 11, Leishman dropped in birdies on 12 and 13 to move into the lead at 13-under. He parred three in a row before dropping his third shot within five feet at the par 5 17th.
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Leishman rolled that putt in for birdie to get to 14-under. He parred the last to finish one shot off the tournament's 36-hole scoring record.
'That's big around here because there's five of them,' said Leishman, who birdied all five par-fives. 'I birdied four of them yesterday. I've been playing ok, but the biggest challenge is that I have never seen most of the courses. You make a few silly mistakes and hit it in the wrong spots, but it's starting to come together. The last few weeks have been pretty good.'
Thompson played the back nine first and parred his first four holes. He birdied 14 and 15 to move to 9 under.
Around the turn, Thompson birdied the first and third to move into a share of third place. Birdies on seven and eight got Thompson within one of Leishman. Thompson missed a birdie putt at the ninth, his last, to end alone in second.
Television commentator Bobby Clampett carded a 67 to move into sixth place.
Putnam's 63 moved him into a share of eighth. He was joined there by 12 others.
Bubba Dickerson carded a hole-in-one on the par-3 18th. After four aces on Thursday, the five holes-in-one for the event set a Nationwide Tour record for most aces in one tournament.
The cut line fell at four-under-par 138 with 63 players moving on to the weekend. Among those missing the cut were the Nationwide Tour's leading money winner Brendon De Jonge (139), No. 5 on the money list Rick Price (142) and Scott Dunlap (149), who won the Panama Championship earlier this year.