'It was the best golfing day I ever had,' said Ahern. 'You have to cherish when you have days like this.'
Ahern led by one after the opening round and vaulted out of the gate Saturday with an eagle at the par-5 first. Ahern continued to role with a birdie at the second and drained a 30-foot putt for a birdie at the third to make it two in a row.
He two-putted for birdie at the par-5 sixth and added a birdie at the eighth. At the par-4 ninth, Ahern hit a pitching-wedge from the rough to within two feet for another birdie and a front-nine total of 29.
Ahern kept things going on the inward half with a birdie at the 11th after his approach stopped two feet from the hole and made it two straight with a birdie at the 12th.
The 54-year-old hit a 5-iron to three feet for a birdie at the 14th to move to 10-under par on his round. With 59 in sight, Ahern cooled off down the stretch and three-putted the 18th for a closing bogey.
'I just went to sleep on 18,' said Ahern.
Ahern needed only 24 putts on his round and stands ready to become the first wire-to-wire winner on the Champions Tour this season.
'Stan Utley helped me with my putting in Kansas,' said Ahern. 'I made some drastic changes and have been working hard at it. To compete out here you have to be a good putter.'
Jose Maria Canizares shot a 7-under 65 to finish in a tie for second with Rodger Davis at 11-under-par 133.
'Jim has played fantastic golf today,' Canizares said of Ahern. 'It's difficult to catch a guy playing like that. Tomorrow you'll have to shoot 61 or 62 and Jim maybe shoots 71 or 72. It's not easy.'
Jim Holtgrieve and Tom Jenkins finished tied for fourth at 10-under-par 134. Hugh Baiocchi was one shot further back at 9-under-par 135.
R.W. Eaks had the second-lowest round of the day with a 64. He was joined by Ed Dougherty, Larry Nelson, Morris Hatalsky and J.C. Snead at 7-under-par 137.
Hale Irwin, Dave Barr, Dave Stockton, Ed Fiori and Doug Tewell were one shot further back at 6-under-par 138.