Playing on a protected ranking after slumping to No.785 in the world, Gavrilova sent 24th seed Dayana Yastremska packing with a 6-4 6-3 boilover on a chilly and wet first day at Roland Garros.

Gavrilova only made her comeback two weeks ago from more than a year out battling a debilitating foot injury and entered the claycourt slam with modest hopes.

But the one-time world No.20 needed only one hour and 21 minutes to see off Yastremska and book a date with former Wimbledon finalist Eugenie Bouchard.

"It's pretty cool. It's pretty satisfying," Gavrilova told AAP.

"I was pretty confident, to be honest. I played a very confident match.

"I kind of knew what to expect from her and I did everything right and I was very positive - the old Dasha was back.

"I felt like it all started again. I was very hungry and I was really enjoying every moment. Yeah, it was fun."

Gavrilova was under the tutelage of David Taylor, the long-time former coach of 2010 French Open runner-up and 2011 US Open champion Samantha Stosur, before aborting her 2019 season last September.

In a quirk of fate, Taylor's latest charge was Australia's only other winner on day one.

And Astra Sharma's breakthrough was equally as unexpected as Gavrilova's.

Sharma only gained entry to main draw as a "lucky loser" from the final round of qualifying.

But the 25-year-old is now at least $140,000 richer after securing the biggest pay day of her career with a 6-3 2-6 7-5 victory over Russian Anna Blinkova.

"Super thrilled," Sharma told AAP.

"It was really tough conditions, really rainy. The balls were really soaked, the court was pretty wet so you'd hit a regular shot, the ball wouldn't go anywhere.

"But I was pretty happy with the way I handled everything and the way I kept it together and tried to find a way to win out there.

"After not such a good last round in qualifying, to bounce back like this and get a result like this is pretty gratifying."

Sharma's reward is a shot at another Russian, Ekaterina Alexandrova, the 27th seed who ousted fellow Australian Maddison Inglis 6-3 6-3.

While Gavrilova and Sharma march on, their more-fancied compatriots Alex de Minaur, Jordan Thompson and Ajla Tomljanovic all bombed out.

A US Open quarter-finalist only two weeks ago, de Minaur crashed to a 7-6 (11-9) 6-4 6-0 loss to Italian qualifier Marco Cecchinato after blowing two set points in the opening tiebreaker.

Thompson, who reached the third round last year and fresh off his own career-best run to the last 16 at Flushing Meadows, suffered a crushing 6-2 6-4 6-1 loss to Moldova's Radu Albot.

Tomljanovic, the top-ranked Australian in the women's draw in the absence of world No.1 and 2019 champion Ashleigh Barty, went down 6-0 7-5 to in-form Greek Maria Sakkari.

HOW THE AUSSIES FARED ON DAY ONE OF THE FRENCH OPEN (PREFIX DENOTES SEEDING)

Men's singles, first round

25-Alex de Minaur lost to Marco Cecchinato (ITA) 7-6 (11-9) 6-4 6-0

Jordan Thompson lost to Radu Albot (MDA) 6-2 6-4 6-1

Women's singles, first round

Ajla Tomljanovic lost to 20-Maria Sakkari (GRE) 6-0 7-5

Daria Gavrilova bt 24-Dayana Yastremska (UKR) 6-4 6-3

Maddison Inglis lost to 27-Ekaterina Alexandrova (RUS) 6-3 6-3

Astra Sharma bt Anna Blinkova (RUS) 6-3 2-6 7-5

Australian Associated Press