'To win out here lets me know I can win on the PGA Tour,' said Isenhour. 'I think the Nationwide Tour is the second best in the world and this is one of the biggest tournaments on tour. So needless to say, this is huge.'
Jack Nicklaus posted a 2-under 70 on Sunday at the Cliffs Valley course and in the process finished in a tie for 59th at 4-under-par 283 in his first ever start on the Nationwide Tour.
'It was a better round but not competitive enough,' said Nicklaus, who played with all four of his sons and won the Pro-Celebrity Division tournament with son Steve. 'The boys and I all enjoyed this week. Steve and I have played together probably 20 times and this is the first time we've ever won something. We'll be back next year. It's always nice to come back and defend.'
This tournament has been plagued by weather problems all week. The third round was completed Sunday morning and the final round began immediately after tournament officials determined a final round could be played without any weather problems.
Isenhour began the final round with a three-shot lead and no player was able to make a move up the leaderboard. Isenhour rattled off eight pars to begin the round before a 15-foot birdie putt at No. 9.
Isenhour parred 10 and 11 and put the tournament away shortly after the pars on his second nine. He wedged his approach to a foot at the 12th and he sank a 25-footer for birdie at 13 to pull ahead for good.
He parred the last five holes of his round to earn his first victory of 2003 and his second on the Nationwide Tour.
'I knew I had a lead starting out so I knew if I played solid they would have a hard time catching me,' said Isenhour, who won the 2000 Nationwide Mississippi Gulf Coast Open. 'I was playing solid so I didn't get caught up in what others were doing.'
Isenhour pocketed $103,500 for the win and moved from 63rd on the Nationwide Tour money list to third.
Thompson carded a final-round 66 for his third top-10 on the Nationwide Tour in 2003.
Paul Claxton finished third at 15-under-par 272, followed by John Curley (66), leading money winner Joe Ogilvie (67), Jason Dufner (68) and last week's Rheem Classic champion Zach Johnson (69). That group stands shared fourth at 13- under-par 274.