Ashleigh Barty is doing her best not to get ahead of herself after the Australian's path to a French Open crown was spectacularly cleared.

Key points: Australia's Ash Barty has made it to the fourth round at Roland Garros with a straight sets win over Andrea Petkovic

Australia's Ash Barty has made it to the fourth round at Roland Garros with a straight sets win over Andrea Petkovic The Queenslander has yet to drop a set at the tournament — she will next play unseeded American Sofia Kenin

The Queenslander has yet to drop a set at the tournament — she will next play unseeded American Sofia Kenin Kenin knocked out American superstar Serena Williams, while defending champion Naomi Osaka was beaten by Katerina Siniakova

The world number eight calmly booked a spot in the round of 16 with a 6-3, 6-1 defeat of Andrea Petkovic on the same day Serena Williams and world number one Naomi Osaka fell.

Williams was slated to face Barty next as she pursued a record-equalling 24th grand slam title while Osaka — Barty's projected quarter-final opponent — had won the last two slams.

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Instead, Barty will play world number 35 Sofia Kenin after the 20-year-old fearlessly blasted compatriot Williams off the court.

The winner of Madison Keys or Osaka's conqueror Katerina Siniakova would be Barty's quarter-final opponent, with defending champion Simona Halep (third seed) and last year's finalist Sloane Stephens (seventh seed) the only higher-ranked women in the draw.

Former champion Garbine Muguruza is another lurking in the bottom half of the draw, due to play Stephens on Sunday.

Barty, 23, has made a career of not thinking too far ahead and won't start now as she hunts Australia's first French Open title since Margaret Court won her fifth in 1973.

"For me it's easy not to look ahead," Barty said.

"Obviously there's talk and it's unavoidable to hear what else is happening around the draw. But for me, I can't control any of that. I can't control what other girls are doing.

Day seven results Naomi Osaka (1) lost to Katerina Siniakova 4-6, 2-6

Naomi Osaka (1) lost to Katerina Siniakova 4-6, 2-6 Simona Halep (3) def Lesia Tsurenko (27) 6-2, 6-1

Simona Halep (3) def Lesia Tsurenko (27) 6-2, 6-1 Ash Barty (8) def Andrea Petkovic 6-3, 6-1

Ash Barty (8) def Andrea Petkovic 6-3, 6-1 Serena Williams (10) lost to Sofia Kenin 2-6, 5-7

Serena Williams (10) lost to Sofia Kenin 2-6, 5-7 Novak Djokovic (1) def S Caruso 6-3, 6-3, 6-2

Novak Djokovic (1) def S Caruso 6-3, 6-3, 6-2 Dominic Thiem (4) def Pedro Cuevas 6-3, 4-6, 6-2, 7-5

Dominic Thiem (4) def Pedro Cuevas 6-3, 4-6, 6-2, 7-5 Alexander Zverev (5) def Dusan Lajovic (30) 6-4, 6-2, 4-6, 1-6, 6-2

Alexander Zverev (5) def Dusan Lajovic (30) 6-4, 6-2, 4-6, 1-6, 6-2 Juan Martin del Potro (8) def Jordan Thompson 6-4, 6-4, 6-0

Juan Martin del Potro (8) def Jordan Thompson 6-4, 6-4, 6-0 Borna Coric (13) lost to Jan Lennard Struff 6-4, 1-6, 6-4, 6-7 (7/1), 9-11

"I can only control how I prepare, how I play, and ultimately how we go about my next match."

Williams came from a set and a break down to beat Barty in the second round in Paris last year but the Australian wasn't fussed about the rematch falling through.

"You can only play who's on the other side of the net," she said.

"There's so much talk around the draws when they come out, and so much changes every single day.

"You have to take absolutely nothing away from Sofia.

"She's played an incredible match, obviously, to beat a world-class champion. And the challenge will be just as great coming from her as it would have been if it was Serena."

Serena Williams' French Open bid to match Margaret Court's record of 24 grand slam titles has come to an end. ( AP: Christophe Ena )

Williams failed to recover from a woeful start against fellow American Kenin as the 20-year-old motored into the last 16 with a 6-2, 7-5 win, putting the former world number one's quest for a record-equalling 24th singles major on hold.

Williams, who suffered her earliest Grand Slam exit since Wimbledon 2014, was given a standing ovation as she walked off Court Philippe Chatrier while sections of the crowd jeered her conqueror.

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The 37-year-old Williams, seeded 10th, paid the price for her lack of match practice as she was playing in only her fifth tournament of the year, and her fightback in the middle of the second set was short-lived.

Osaka, just like Williams, was a possible semi-final opponent for third seed Halep, who is looking to become the first woman to retain the Suzanne Lenglen Cup since Justine Henin won a third consecutive title in 2007.

But the Japanese top seed, who had already been forced to go the distance in her first two rounds, was clueless in a 6-4, 6-2 defeat to Czech Katerina Siniakova.

The loss snapped Osaka's 16-match winning streak in Grand Slams after she won the 2018 US Open and this year's Australian Open.

It's been a bad week for favourites in the women's singles, and now top seed Naomi Osaka has gone as well. ( Reuters/USA TODAY Sports: Susan Mullane )

With Osaka gone, five of the top six seeds are now out of the women's singles draw, leaving Halep as the sole survivor.

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The Romanian showed her best side in a 6-2, 6-1 dismissal of Ukrainian 27th seed Lesia Tsurenko.

Barty was business-like in beating Petkovic, resisting some early pressure to claim five straight games and lay the path to victory.

She hasn't lost a set in her three victories so far.

"I've been able to close out matches well," Barty said.

"I've been able to win some matches in business-like fashion, but they're certainly not easy matches, that's for sure.

"I feel like I'm playing well and being able to execute to make the score lines look a little easier than the match actually is."

AAP/Reuters