Chalmers, the 215th ranked player in the world leading into this week's event, won by one shot over 54 hole leader, John Senden, with Tiger Woods bouncing back from his unfathomable round yesterday for a closing 67 to finish outright third.
Geoff Ogilvy, Adam Scott, Nick Watney, Nick O'Hern and Jason Day all shared 4th position with Aaron Baddeley and surprise packet Ryan Haller rounding out the top ten.
Chalmer's fast start today with birdies at the opening two holes gave him a share of the lead and, when Senden bogeyed his second hole soon after, Chalmers stood alone at the top of the leaderboard.
Senden's playing partner and closest pursuer at the start of the day, Jason Day, was another to begin poorly, dropping shots at his opening two holes and although he would recover briefly before the turn, bogeys early in the back nine cost him any real chance.
Chalmers three putted the 9th to turn in 34 and at 11 under he shared the lead with Day but perhaps the most crucial shot of the day may well have been his tee shot at the par three 15th. Having just missed a good birdie opportunity at the 14th, his tee shot finished less than two feet from the hole and the resulting birdie took him to 13 under and two ahead.
"I had just slightly pulled both my second and my putt on the 14th and did not birdie there which is a sin on this golf course, said Chalmers after the round. "The 15th really suits me as I move the ball from left to right and the wind was off the right so I hit 7 iron and my goal was to keep it just right of the hole and I did that and it bounced down and I was really happy see it by the hole."
He played the par five 17th smartly avoiding any real danger after driving it in the rough and further highlighted his great bunker play skills by getting up and down at the 72nd hole for par. At that point he stood two ahead of Woods and Senden, the latter of who had staged a remarkable recovery after his horror front nine and who was playing the 17th.
Senden birdied the 17th from 5 feet to keep his chances alive. He would have to birdie the last however if he was to force a playoff and after his tee shot finished 35 feet beyond the hole his chances seemed remote at best.
As Chalmers watched on, Senden hit a beautiful putt but as it slid by his one remaining chance had disappeared. Chalmers was therefore confirmed as the winner.
"I felt like my game was in good shape and coming into the week the focus on a whole bunch of different players and I wasn't one of them," said Chalmers responding to a comment that he slipped under the radar a little this week.
Chalmers was asked about his family, several of whom are still back in his US home of Dallas, and the emotion he had shown during the presentation ceremony. "The only point I was trying to make and I wish I had been calmer when I was doing so then was I don't get to this point without the people around me.
"I used to play it for myself now I play it for them. Now of course I have Colin Swatton as my coach who also coaches Jason Day and he has been a big part of my life for the past four years.
"Also Neale Smith from Process Performance helps the mental side of my game and I have known my caddie I have know for 22 years and so he is a big part of the team also and my family. It doesn't happen without them.
"I am just extremely excited and pleased to have won this tournament twice. To have won it once I can see how guys stumble into that but to have won it twice, against this week's field and get it done by shooting 8 under over the weekend really floats my boat."
Comparing this win with the one in 1998 Chalmers responded; "I know more now. I think I stumbled into it when I was 26 and had no real idea how big of a deal it was then. I know more now and how important this event is and just how important it is to win and I now have a strong respect for that now."
Tiger Woods found a way to right the wrongs of yesterday when he raced to the turn in 32 and was threatening danger to those behind him on the golf course. He again made a mess of the par five 11th but added another birdie at the 12th before indecision from the tee cost him a crucial shot at the 13th.
He then chipped in for eagle at the par five 13th and at that point it appeared he might be on the way to a stunning but he would add only one more birdie at the 17th and Chalmers responded to the threat.
"The 13th I should not have taken a driver "“but I figured I needed a 31 to give myself a chance because 13 or 14-under would be the number. I had to go get it and unfortunately made a mistake.
"I hit the ball really good. Two bad tee shots on the back nine "“ making bogeys but other than that I controlled it pretty much all day. The 13th I should not have taken a driver "“but I figured I needed a 31 to give myself a chance because 13 or 14-under would be the number. I had to go get it and unfortunately made a mistake.
"We did some work last night and I felt I was close to finding it yesterday but it just wasn't there.
"It has given me confidence for next week. I felt great, it was great to finally be healthy again. From a competitive environment this has been great preparation for next week. I'm a step closer to winning "“ I feel I'm right there."
The Australian Open might not necessarily have gotten the champion it was expecting but Greg Chalmers was tough when the going got tough.
Chalmers has been a regular on the PGA Tour now since 1999 and in many ways deserves more credit than he gets. Perhaps his victory this week might just change that.