MELBOURNE, Australia -- First-round leader
Guyatt, a regular on the Japan Challenge Tour but not well-known in his home country of Australia, had a two-round total of 10-under 134 on the Kingston Heath sand-belt course in south Melbourne.
Defending champion Ian Poulter of England shot 72 on Friday and was tied for fourth, five strokes behind.
"I've left quite a few shots out on the golf course and I'm not very happy," Poulter said.
McDowell shot 77 on Friday and just scraped in for the weekend at 4-over 148, 14 strokes behind. He had six bogeys and a double-bogey Friday.
Guyatt was off the tour for five years, but returned two years ago with the financial backing of a 78-year-old friend who he has not named.
"He just about fell over," Guyatt said when his benefactor found out that he was leading. "I was just hoping he hadn't had a heart attack. He hadn't -- he was very excited. He's had the belief since he first played with me."
A long-time acquaintance of Guyatt, Scott said he was pleased the 37-year-old, ranked 1,474th in the world, was playing well.
"Matt's worked hard for a long time so anything he gets he thoroughly deserves," Scott said. "I wish him all the best for the next two days, but I'll be gunning for him."
Guyatt said he would be comfortable on Saturday in the final group with Hendry.
"I actually said to my caddie -- it was looking like Mike Hendry might be the guy I get paired with. I said that wouldn't be bad because I've travelled a little bit on OneAsia this year with Mike and get along well with him," Guyatt said.
"That might be a good initiation into the final group rather than a Poulter or an Adam Scott or someone like that where the crowds are going to be heavily increased."
Guyatt said his first two rounds had given him confidence for the weekend.
"That's the battle, I think, that players in my position face," he said. "The belief that you've got enough game, the belief that you're good enough. I think I'm starting to get there."