Don Pooley, the 2002 U.S. Senior Open Champion, stumbled to a 2-over 74. He shares second place at 1-under-par 215 with Mark McNulty, who also shot a third-round 74. Mark James, the Ford Senior Players Championship winner, and 1992 U.S. Open Champion Tom Kite share fourth place at even-par 216.
Oakley opened the round in a share of the lead and remained there with a birdie at the par-5 second. He dropped back to minus-2 after bogeys at the fourth and sixth.
The 55-year-old picked up a pair of birdies at the ninth and 11th at Royal Portrush Golf Club to move back into the lead at 4 under.
Oakley, however, faltered to consecutive bogeys from the 12th to slide back to minus-2. He parred his final five holes to remain atop the leaderboard.
'Today I was a little bit antsy getting ready to tee it up with Tom Kite and Mark James, who are names I've heard of and watched on television and have admired for so long,' Oakley said. 'I felt comfortable and fairly relaxed and I played fairly well.'
Oakley, the 1999 PGA Senior Club Professional Champion, is a club professional who is the director of golf at the Rookery in Delaware.
'I won the 1999 American PGA Seniors Club Professional Championship and I finished second the next year,' said Oakley, who has played in 16 major championships. 'Those are basically my credentials, as far as playing is concerned. I tied for 29th at the U.S. Senior Open last year, that's about the best I've done.'
McNulty shared the lead entering round three with Oakley, Pooley and Carl Mason. McNulty opened with a bogey at the first and a birdie at the second. He faltered to a bogey at the third and a double bogey at the fourth to fall to even par.
The Irishman came back to birdie the fifth before he dropped another shot at the eighth. McNulty settled in with three straight pars, then dropped in back-to-back birdies from the 11th.
McNulty bogeyed the 14th and 16th to again drop to even par. He moved into a share of second place with a birdie at the last, one of just seven on the day at the 18th.
'I would certainly put it down as one of the toughest days I have had in my career,' said McNulty, who is playing his first event in Northern Ireland as a Irish citizen. 'I had some silly mistakes and in the beginning of my round, I just lost my swing and didn't feel comfortable.'
Pooley birdied the second for the third straight round before dropping a shot at the sixth. He birdied the ninth for his final birdie of the day. He closed with three bogeys over his final four holes to drop into a tie for second place.
'I played solidly for 14 holes and hit a good drive on 15. Then I hit a bad 4-iron into a bunker on my second shot and didn't get it up-and-down and made bogey,' Pooley said. 'I'm happy being right where I am, but man, I'm not happy with my finish.'
Eduardo Romero, who shared the lead after Round 1, carded a 2-over 74. He shares sixth place with Bill Longmuir (76) at 2-over-par 218. John Grace and Bobby Lincoln are two strokes behind that duo.
Mason struggled to a 9-over 81 to fall to 6-over-par 222. Mason is joined there by Graham Marsh, who made some history on Saturday.
Marsh aced the par-3 11th for the second time in three days making him the first player to have a hole-in-one on the same hole in a top flight tournament. It is the first time in PGA, European PGA, European Seniors and Champions Tour history that this feat has been achieved.
'There's no better prize I could have been given, being a wine connoisseur,' said Marsh, who received one bottle of wine per yard (170) as Hardys Wine is the hole-in-one sponsor. 'This could about take me out of professional golf. It's a freaky situation.'
Tom Watson, the 2003 champion, posted his second straight 74 to slide into a tie for 20th at 7-over-par 223. Watson has been battling injuries that nearly held him out of this event.