On a remarkable day of Aussie upsets Adam Walton and Kim Birrell recorded the biggest wins of their careers to march into the second round of the French Open with a pair of top 10 scalps.

Meanwhile Alex de Minaur was handed a walkover into the third round after his would-be Belgian opponent, world No.37 Alexander Blockx, was forced to withdraw due to an ankle sprain.

Home Hill hero Walton, 27, survived a seesawing five-setter against sixth-seed Daniil Medvedev, rallying from a break down in the fifth to prevail 6-2, 1-6, 6-1, 1-6, 6-4.

Fellow Queenslander Birrell, 28, followed suit just hours later, knocking off in-form fifth-seed Jess Pegula 1-6, 6-3, 6-3.

Walton had never won a five-set match in Paris before ousting Medvedev on Tuesday, in humid conditions that played perfectly into the Aussie underdog’s hands on Court Suzanne-Lenglen.

The world No. 97 traded one-sided sets with his Russian rival, who he had previously defeated on a hard court in Cincinnati last year.

“I had the belief that I could definitely go out there and beat him,” Walton said.

“Obviously having done it in Cincinnati was a huge confidence booster.

“To get a first top 10 win at a slam is pretty epic.”

After going down 3-1 in the fifth set Walton survived further break points before rattling off four-straight games to consign Medvedev to his sixth first-round defeat in nine appearances at Roland Garros.

“I think if I lose that game to go 4-1 double break I’m probably not a winner today,” Walton said.

“Anyone can beat anyone on a given day – for sure it’s a big confidence boost.

“I think also to do it in a five-set format is harder to beat the top guys so yeah, just really proud of my efforts.

“I do feel that every time I go back onto the clay I get a little bit more comfortable on it.”

In the early hours of Wednesday morning Birrell fought back from a set down to overwhelm world No. 5 and Australian Open semi-finalist Pegula in the first big upset in the women’s draw.

It was the Gold Coaster’s third career win over a top 10 opponent and first on clay, declaring she felt “inspired” by Walton’s upset earlier in the day.

Pegula played near-perfect tennis to take the first set in just 24 minutes and was in control after breaking Birrell early in the second.

But the Aussie broke back with a deft drop shot that brought Court Simonne-Mathieu to its feet and breathed life into her comeback.

“I’m glad I had the courage to take the opportunity – I saw that she was quite far back in the court and hit the drop shot, which I think in the past I probably wouldn’t have had the courage to do,” Birrell said.

“I’m just really proud that I was able to play this well on a surface that doesn’t feel that familiar to me, to be honest.”

Walton will meet American Zachary Svajda in the second round on Thursday, while Birrell will face Ukrainian Oleksandra Oliynykova.