Aaron Baddeley, Tom Byrum and Andy Miller are one stroke further back at 11- under-par 205. Lickliter and Byrum are the only two players in the top-10 that own PGA Tour victories.
Lickliter played a solid round while Campbell and Flesch made big charges at his lead. Campbell fired a third-round 63, while Flesch at one point was 10-under through 14 but a double-bogey at 15 killed his momentum and he finished with a round of 8-under 64.
Lickliter, who had recorded the lowest 36-hole total on the Omni Tucson National Golf Resort and Spa, opened with four straight pars before a four-foot birdie putt at the par-4 fifth. The 33-year-old then parred six and seven before rolling in a 20-footer for birdie at the par-5 eighth.
'I was just trying to be patient on the front nine,' Lickliter said. 'I was just trying to roll the ball with a good speed.'
Around the turn, Lickliter made a 25-footer for birdie at the 10th to move to minus-17 for the tournament. He then parred seven straight holes before faltering with a bogey at the last when he missed a five-footer.
'I played real solid today,' said Lickliter. 'I missed a few greens, but was able to get them up-and-down. I'm happy with the way I played and I was able to stay real focused today.'
Lickliter has led twice after 54 holes and he turned one of them into his lone victory at the 2001 Kemper Open. At this tournament, 30 of the 53 players who have led after 54 holes have gone on to win.
Campbell, who started in the first group of the day, began his round with consecutive birdies starting at the second. Campbell then parred the final six holes on that side to make the turn at 5-under for the tournament.
The three-time winner on the Nationwide Tour then made his move. Campbell recorded back-to-back birdies starting at the 11th. After a par at 13, he ran off five straight birdies to close out a career-low round and a back-side 29.
Flesch had a chance to shoot in the 50s, but that dream ended on 15. The lefthander came roaring out of the gate with four straight birdies starting at the second. He then notched consecutive birdies from the seventh, both from within 15 feet, to make the turn at 6-under for the round.
The former University of Kentucky Wildcat continued to roll on the back side. He ran off four straight birdies for the second time in the round starting at the 10th, including lengthy putts at 11 and 12, to climb to 10-under for the round.
'It was hard not to get ahead of yourself at that point (10-under through 13),' said Flesch. 'You think about it but to get to 10-under I had a lot of really fortunate things happen with some long putts going in.'
Flesch's thoughts of breaking 60 all but came to an end at the 15th where he posted a double-bogey after dropping his third shot at the par-five in a bunker, then he three-putted once on the green. Flesch parred in for a round of 64.
'I really haven't played that well this year so far,' Flesch said. 'I've always played well here so I look forward to tomorrow and I'm back in position where if I play really well I have a chance to catch Lickliter.'
Jeff Brehaut, Carlos Franco, Tim Herron, Kent Jones, Andrew Magee, Arron Oberholser and Bob Tway share eighth place at 10-under-par 206. The University of Arizona's Ricky Barnes, playing as an amateur, is tied 15th at 9-under-par 205. Jeff Klein and Graeme McDowell are tied with Barnes.