Former world number one Ernie Els has set his sights on overhauling Tiger Woods in the next three years, even if it means missing out on a title in the short term.

Els must reel in his compatriot Trevor Immelman over the final 18 holes of the South African Airways Open at the Humewood Golf Club in Port Elizabeth to win his first tournament of the year.

The latter shot a course record of 63 today to go into the final round with a three-shot cushion.

In complimenting his playing partner's round as "the best I have ever seen him play", Els then committed himself to the duel on the final day before revealing his ambition to claim the world number one spot from Woods in the next few years.

"I know what I have to do in the last round and I'm feeling good at the moment. I was very hard on myself in the past few weeks but this week I'm feeling good about my game again," Els said.

"I'm not pressurising myself so much and I will go for it. If it happens that's great.

"If it doesn't happen, then so be it. I'm focusing on my goal at the moment. I have much bigger goals that I am aiming for at the moment, like I want to be number one in the next three years. I've given myself three years to reach those goals."

Els has endured a torrid year where his game has been far from his normal high standards.

He has dropped out of the top three and currently sits at number eight on the world rankings. However this past week there have been some wonderful glimpses of his best.

But even that was overshadowed today by Immelman, who celebrated his 27th birthday with a near flawless round.

The showdown is widely anticipated although there was some disappointment at defending champion Retief Goosen's form in the third round.

Although steady, Goosen posted a 68, and on a day where few went over par, it left him with a mountain to climb, some seven shots behind Immelman's mark of 20 under.

Sweden's Patrik Sjoland ended the day with a 69, five off the pace while Englishman and first round leader Andrew Raitt was alongside Goosen on 13 under. Darren Fichardt's 65 moved him into joint sixth place alongside Lee Westwood, who shot his third consecutive 68 for a 12 under total of 204.

Immelman admitted he had benefited from being in Els' presence and it had
lifted his game.

"It was a great day for me, obviously every time you can shoot a good round
in Ernie's presence," he said. "It was a fantastic feeling. You obviously know how much I look up to him and still do.

"So for me to perform in that way was a great feeling. I wasn't too pleased with my ball striking yesterday even when I managed to grind out a pretty good score.

"Today I really managed my game really well and managed to keep my drives in play and my iron shots to the right side of the flag for me to make an aggressive putt.

"My putter really did a great job. I got a nice putting tip from Frosty (David Frost) a couple of weeks ago. I've been working on that and it's great that I am starting to hole some putts."

Former Dunhill Championship champion Charl Schwartzel clawed his way up the leaderboard after an impressive morning with a 65 to move to 11 under and was joined there by an equally impressive 66 by Englishman Ross Fisher.