Starting the day five shots up on fellow Australian Rod Pampling, Senior bogeyed the 17th to give him a brief three-shot cushion over Pampling, who missed a birdie putt on 17 that could have narrowed the margin to just two shots.
On 18, Pampling's tee shot sat only a foot from the lake the borders the left side of the fairway. He pitched out and made bogey just moments after Senior landed a 50-foot putt for birdie to restore his five-shot lead going into Sunday's final round.
One of Senior's closest pursuers is former University of Houston player Wade Ormsby, who tied the Hyatt Regency course record Saturday with a 9-under 63.
Senior has a three-round total of 18-under 198 while Pampling, Ormsby and Craig Parry are tied for second at 203. Parry had a 68 Saturday and Pampling 69.
Ormsby, 23, improved on his 73 from Friday to tie Stuart Appleby's 63 from the 1998 Coolum Classic on the Australasian tour. Both Ormsby and Appleby had nine birdies and no bogeys in their rounds.
Australians Scott Gardiner (65) and Peter O'Malley (69) are tied for fifth.
American Ryan Palmer is alone in seventh place at 10-under 206 after a 68 Saturday. Greg Norman and France's Jean Van de Velde are among a group of six at 9-under 207, Norman after a 66 and Van de Velde following his third-straight 69.
American Rich Beem shot a 73 Saturday and has a 1-under total of 215, 17 strokes back of Senior.
Senior will be trying to win his first tournament since the 1997 Canon Challenge in Sydney.
'You bet I'm looking forward to it,'' said Senior. 'If I happen to win on Sunday, you won't see a happier chappy.''
'The tournament is there for me to win. The most important thing for me is to keep the ball in play and capitalize on the easy holes. I think if I shoot a 68 or 69 on Sunday, it will be very difficult for those guys to catch me.''
Ormsby, who played collegiate golf at Houston for three years, is on a sponsor's invitation here just three weeks after finishing second in the European Tour qualifying school in Spain where one of his six rounds was a 63.
He'll begin play on the European Tour in January at its opening two events in South Africa.
'I knew I was playing well, and I was frustrated when I finished yesterday,'' said Ormsby. 'But I knew it was somewhere in the bag.''
When told he had tied the course record, he said: 'First I've heard of that, bonus.''
Ormsby said the key to his round was good putting after a shaky start.
'I holed a lot more putts,'' said Ormsby. 'I hit a really bad wedge shot into No. 2 but I had a really good line and holed the pitch shot. It was dead center, and from there I didn't look back.''
Ormsby said he tried to 'feed off'' his nervousness late in the round and 'turn it into good stuff.'' On 17 and 18, he hit perfect drives, and on the last hit his approach to one foot for a tap-in birdie to equal Appleby's record.
Ormsby's father Peter is a close friend of Senior's and Ormsby has known Senior since he was three years old. They will be in the final pairing Sunday.
'I think anyone can be caught,'' Ormsby said of Senior. 'But you've got to go out there and play your own game and hope it works out.''
Copyright 2003 Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.