Sam Stosur keeps Australia's hopes alive after Nick Kyrgios falls in straight sets

Samantha Stosur is the last Australian standing at the French Open, after leading men's hope Nick Kyrgios suffered a straight-sets flame-out at the hands of local hero Richard Gasquet.

Stosur produced some of her best tennis in years as she advanced to the fourth round with a superb upset win of last year's finalist Lucie Safarova.

Bidding to become the first Australian male since Lleyton Hewitt in 2007 to reach the fourth round at Roland Garros, 17th seed Kyrgios complained about a shoulder injury as well as the presence of brother Christos in the players' box.

Kyrgios required attention from a trainer just three games into the 6-2 7-6 (9-7) 6-2 loss as he struggled with the shoulder complaint.

Even at full fitness Kyrgios would likely have found life difficult against Gasquet, whose exquisite backhand was causing the 21-year-old considerable trouble.

Kyrgios made 44 unforced errors to Gasquet's 17 in the clearest difference maker between the pair as he capitulated in two hours and ten minutes.

But he was clearly well below his best, saying the injury affected both his backhand and serve while admitting to a trainer that it was getting "dramatically worse".

Having fallen behind 3-0 just eight minutes into the match, the explosive star spent time at the change of ends massaging his left shoulder and called on a physio to offer treatment.

"This morning when I was warming up I could feel it on my backhand, now it's on my ball toss," Kyrgios told the trainer, while wincing in pain at the treatment.

It proved to help little, as he was broken twice more to lose the set in a brisk 31 minutes.

A clearly frustrated Kyrgios incited a chorus of boos from the partisan French crowd after smashing his racquet against an advertising board next to his seat as he tried to regain his composure before the second set.

There were concerned looks on the faces of his support team, including brother Christos who appeared to be the focal point of Kyrgios' anger after losing a tense second set tiebreaker.

"Get out of my box. Get out of my box," Kyrgios shouted.

The exit of his brother from the stands did little to turn around Kyrgios' fortunes, with Gasquet securing a break in the third game of the third set.

Struggling to keep up with Gasquet, Kyrgios was broken again to go down 5-2 allowing Gasquet, who holds a 3-0 record on clay against the Canberran, to serve for the match.

"It's great for me to win against Nick in three sets," Gasquet said.

"He's one of the biggest players now, played very good last two months.

"Of course it's a big victory, especially for me on centre court at home with my crowd."

Meanwhile, Stosur wound back the clock in her 6-3 6-7 (0-7) 7-5 win - just her fourth against the 11th seed Safarova from 15 matches.

"It was very close right from the first game - Lucie and I typically play matches like this one," Stosur said.

"For me to get through this one, I'm really, really happy with how I played."

Stosur will now turn her attention to a fourth-round clash with sixth seed Simona Halep on Sunday.