Two gutsy breakthrough wins have Sam Stosur believing her season is finally spluttering into life in time for her Australian Open campaign.

Stosur followed up a scrappy first round effort at the Hobart International with a never-say-die third-set tiebreaker win over world No.54 Kristina Mladenovic to reach the quarter-finals on Wednesday.

The top-seeded Australian saved two match points in the decider for a gritty 6-4 2-6 7-6 (9-7) second-round win.

“Any win’s a good win but when you’ve got to really tough it out and battle through a long match … if you’re winning 7-6 in the third you’re probably holding your nerve pretty well,” Stosur said.

The world No.17’s gamble to shake up her Open preparations looked not to have paid off when she lost all three matches at the season-opening Hopman Cup.

She brought plenty of rust to Hobart, where she hasn’t played for close to a decade, and only just saw off American qualifier Madison Brengle in the first round.

But the 29-year-old said her game had begun coming together over the five matches as she looks to put years of disappointment at her home grand slam event behind her.

“Midway through that second set it actually felt like things were coming out a little bit cleaner, a little bit more solid,” she said.

“I actually felt better about things but I lost it 6-2.

“I think the third it was probably the best tennis I’ve played this week.”

Stosur’s best effort in Melbourne is the fourth round in 2010, the year before she won the US Open, and last year she was bundled out in the second.

“It’s nice that now I’ve won a couple of matches going into Melbourne but I’m certainly not feeling like I’m ready to leave Hobart just yet,” she said.

Stosur came close to admitting she got out of jail against Mladenovic, saving one of the tall Frenchwoman’s match point with a miraculous backhand that caught the line.

“I think I played two really tough points, maybe hit that slice backhand in by a couple of centimetres but that’s what it takes sometimes,” Stosur said.

She will face a tough assignment against eighth-seed Bojana Jovanovski in the quarters.

Meanwhile, Hobart defending champion Elena Vesnina retired form her second-round match against Spanish qualifier Estrella Cabeza Candela with a hip injury.

The Russian world No.24, who made the fourth round at the Australian Open last year, quit with the score 4-6 6-2 4-1.