Osaka, Japan, 14 October 2013 | AAP

Sam Stosur has won the WTA’s Japan Open title on Sunday with a three-set final victory over Canadian teenager Eugenie Bouchard.

The Australian prevailed 3-6 7-5 6-2 to claim her fifth career title and first since she beat then world No.3 Victoria Azarenka at the Southern California Open final in early August.

“Eugenie was playing really well today. I just had to stick it out in the second set, and I’m pretty happy with how things went in the third,” Stosur said.

“I love playing here. I love the site and the fans are great – I always feel like I have lots and lots of support when I come to Osaka.”

Third-seeded Stosur had to dig deep to overcome one of the game’s brightest young talents, who was playing in her first WTA final.

The 29-year-old could only convert seven of her 15 break point opportunities but eventually won in two hours and 13 minutes at the Utsubo Tennis Centre in Osaka.

Stosur, whose rank has dropped from a season-opening No.9 to her current No.20, lost her only previous clash with the 19-year-old world No.35 last April in Charleston when she retired due to injury while trailing 6-1 2-0.

Stosur’s passage to the decider in Osaka was helped by the withdrawal of top seed Jelena Jankovic just before the tournament started, while second seed Sabine Lisicki pulled out of her second-round clash against Polona Hercog due to injury.

Stosur has now won twice in Osaka, after claiming the inaugural tournament title in 2009.

It’s the first time she has won the same WTA event twice, and also the first time she has captured two WTA titles in a single season.

Unfortunately, Stosur was unable to achieve a second victory on Sunday; contesting the doubles final with partner Zhang Shuaishe fell 6-4 6-3 the French-Italian combination of Kristina Mladenovic and Flavia Pennetta.