But the Gold Creek Country Club teaching professional has vowed to learn from his mistakes and make amends when he targets the Australian Open and Australian PGA over the next two weeks.

Millar fell back to a tie for sixth after holding the lead going into the final round at Huntingdale in Melbourne, with Peter Senior firing a three-under-par round to clinch a two-shot victory.

Millar was left wondering what if as he slipped back in the field as he tried to claw his way back up the leaderboard, finishing with a four-over-par round and three-under for the tournament.

Another top-10 finish and $111,544 in prizemoney this year is nothing to be baulked at for a man who had to win back his Australian tour card earlier this year. But Millar knows he had an opportunity to win the gold jacket.

"It just wasn't a good day which is unfortunate because I felt pretty comfortable and off the tee I hit the ball well, it's just disappointing to not go better," Millar said.

"Especially when the short game is usually your go-to stuff. It's been really enjoyable, being the leader in one of our bigger events and having so much support.

"It's been awesome, I'm glad I led the tournament and I've learnt a fair bit. But right now, I feel a bit sick in the stomach actually.

"Even if I finished solid ... It's not that I can't handle not winning. Pete [Senior] did well. But the way I finished and spending a couple of extra shot, finishing in sixth is not what I'm there for. It's a bit of an ordinary feeling."

Friends and supporters gathered at the Gold Creek clubhouse on Sunday to watch the final round and ride Millar's wave through the last 18 holes.

Had Millar maintained his overnight score, he would have finished outright second and taken home a bigger share of the $750,000 prize pool. Instead he went for broke on the back nine playing catch-up with Senior and in the end pushing shots cost him bogeys on the 12th, 15th, 17th and 18th holes.

It was a disappointing way to end another solid week in Millar's resurgence after he won back his tour card this year. But, Millar now has nine top-10 finishes this year, including a triumph at the New Zealand PGA Championships.

"The putts just didn't go in today, none of them. Nothing was going my way, it was a little frustrating and disappointing and that probably didn't help my finish.

"At 18 I took on a pin that wasn't there to be going at. I hit an average shot into the front bunker. It just wasn't going my way."

Millar, ranked fifth on the Australian order of merit, will line up again at the Australian Open this week. The field has been bolstered by the inclusion of 22-year-old two-time major winner Jordan Speith, who joins Geoff Ogilvy, Lee Westwood and Adam Scott at The Australian Golf Club.

Millar, 39, wants to carry his form and momentum to Sydney, but said his best chance of winning was in Melbourne.

"I'm not ruling out the next two weeks but this weekend was my best chance with the set-up of the golf course, it was right up my alley," Millar said.

"There's no excuses there. I'm not saying [the Australian Open and PGA] don't suit me, but they require a different ball flight to really excel.

"If I play well at The Australian and curb my errors for the week, I can definitely get up there. I've just got to rest up and sharpen up a bit."