The European Tour event in Perth will be using a different format over the four days of competition, with the first three rounds strokeplay before matchplay comes into effect on Sunday.
Two cuts will also be introduced for the tournament, with the field being reduced at the half-way stage, before the 24 leading players after Saturday will head into the final day.
Many are intrigued to see how the participants will deal with the new style but Foster, whose only win on the European circuit came at the 2003 Dunhill Championship, started in magnificent fashion.
The Englishman made seven birdies before just slipping up at the 18th hole when making a bogey, leaving him to sign for a six-under-par 66 at Lake Karrinyup Country Club.
Foster was not in great form before arriving Down Under, having finished tied-31st at the BMW SA Open, but he was delighted with how his opening 18 holes went.
"I'm pleasantly surprised," he told the European Tour website. "You come all this way and you don't know what to expect and, obviously, as the round went on it got better so I was really pleased.
"You just come down, you want to give yourself a chance, so I came down early because I've not been playing anything, so that was the best thing I probably could have done."
Home favourite Brett Rumford has joined Foster at the top of the leaderboard after the Australian also shot a round of 66 and the leading pair will be hoping for a strong start on day two.
There are no less than 10 players currently in a share for third on -5 with Hideto Tanihara, Steve Dartnall, Lucas Herbert, Casey O'Toole, Robert Dinwiddie, Adam Blyth, Jason Scrivener, Sebastian Heisele, Johannes Veerman and Daniel Fox all one shot off the pace.