Rising Australian sprint star Melissa Breen has done just about everything possible to try and secure a spot on the Australian team for the London Olympics.

Everything that is, except better the elusive 100m qualifying mark of 11.29 seconds.

But it hasn't been for want of trying.

By coach Matt Beckenham's reckoning, Breen has had 18 or so runs this year within 0.2 seconds of the Olympic A standard - most of those without luck in adverse conditions - including a season's best of 11.35.

She gets three more cracks this weekend at the Australian championships in Melbourne, where the weather gods are finally set to smile on the 21-year-old.

And if she comes up short again, the workaholic Canberra sprinter is prepared to try again at meets in Japan and the United States before the qualifying cut-off in June.

As it stands right now, Australia could well be without a male or female individual competitor in any flat event below 800m in London.

Beckenham believes the ultra-consistent Breen has already achieved enough to get a discretionary nod from the selectors, even if she can't quite run 11.29 or better in the next two months.

"The argument for me is that she is a developing athlete who has shown glimpses of being one of our greatest sprinters ever," said Beckenham.

"Obviously you've got Sally Pearson who is there at the moment, but Mel is tracking along age-wise where Sally was and we know where Sally has gone on to in the hurdles.

"There is potential there for Mel to be another really good sprinter in this country."

It hasn't been all been smooth sailing for Breen, who clocked a personal best of 11.33 as an 18-year-old in 2008, only to lose form and miss out on competing at the following year's world championships.

She also performed below expectations at the 2010 Commonwealth Games in Delhi, where she was run out in the 100m semi-finals.

"It was make or break time after the Commonwealth Games," said Beckenham.

"We sat down and said 'do you really want to be an international-class runner?'

"And if you do, then we need to fix some of the things that are breaking down under pressure and turn you into an unflappable sprinter.

"So that's what we did."

With the pressure of chasing the 11.29 mark off for a few days last weekend, Breen warmed up for the national titles with an impressive victory off scratch in the women's Stawell Gift.

"This is going to help me so much in the next month to run my A qualifier," said Breen after claiming victory on the grass track in Stawell.

"I know I'm in good shape and I've been heartbreakingly close to the Olympic mark so many times.

"I've just got to get back on track and keep trucking on."

Another runner who faces a potential Olympic D-Day this weekend at Lakeside Stadium is Tamsyn Manou.

At the opposite end of her career than Breen, the 33-year-old Manou is targeting the tough 800m qualifying mark of 1:59.90 against a field including Zoe Buckman, who has already booked her spot on the London team in the 1500m.

Manou is chasing a spot on what would be her fourth and final Olympic team.

John Salvado
AAP