Nicklaus stands at 4-under-par; two shots back of Hale Irwin, who fired a five-under-par 66 on the TPC of Tampa Bay to move to 6-under for the tournament.
Nicklaus is one of six players tied for second place. Gil Morgan (67), Bob Gilder (68), Jose Maria Canizares (68), Bobby Walzel (68) and defending champion Bruce Fleisher (69) are all deadlocked at 4-under.
Dana Quigley recorded the low round of the day in Lutz, Fla., a 6-under-par 65. Quigley is in a six-way tie for eighth place at 3-under.
Nicklaus, 61, is seeking his first victory since the 1996 Tradition, and his 11th overall on the Senior circuit. Saturday, he posted a pair of birdies to offset a pair of bogeys to finish the day where he started.
'I haven't been in the position to win a golf tournament for a long time,' said Nicklaus. 'It would be neat. I'd love to win. It would give me confidence and I would play more. I'd really enjoy it.'
Irwin made his move up the leaderboard on the back nine. After making the turn in 1-under, Irwin birdied holes 11-13. He completed his round by rolling in a 30-footer for birdie at the 18th.
'I feel like my game is not particularly sharp,' said Irwin, who is playing in his first full-field event of the year. 'What's carrying the day is being fresh.'
Irwin bettered Nicklaus earlier in the season at the Skins Game. Though he did so with a little help from Jack. Nicklaus made a putt on the 18th to force extra holes. Had he missed the putt, Gary Player would have won the hole and Nicklaus would have won the event. As it was, Irwin birdied thse 19th hole to win the skins and the title.
Irwin is coming off a four-win season a year ago, which included the U.S. Senior Open. A win this week would vault him into sole possession of first place on the Senior Tour all-time wins list at 30. He currently shares that honor with Lee Trevino.
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