(Photo credit: Mike Frey-Imagn Images)

Three American women -- No. 4 Amanda Anisimova, No. 6 Jessica Pegula and No. 9 Madison Keys -- advanced to the fourth round of the Australian Open with straight set victories on Saturday in Melbourne.

Anisimova defeated countrywoman Peyton Stearns, 6-1, 6-4. Pegula ousted Oksana Selekhmeteva of Russia 6-3, 6-2, while Keys outslugged Karolina Pliskova of the Czech Republic 6-3, 6-3.

Third-seeded Coco Gauff and No. 29 Iva Jovic advanced on the top half of the draw on Friday, giving the United States five players in the round of 16.

Pegula and Keys, who will meet in the quarterfinals, started their matches at 10:30 a.m. local time due to oppressive heat in the forecast for Melbourne.

Keys, the defending Australian Open champion, had the toughest task, facing former world No. 1 Pliskova, who is on the comeback trail. However, Keys jumped out to an early 4-0 lead, survived one break of serve and won all four points on Pliskova's serve in the ninth game to take the first set.

The second set was more tightly contested, but Keys broke serve in the eighth game and reached the finish line in 75 minutes.

Keys has won her past 10 matches in Melbourne.

'Overall, I think I played pretty well,' she said in her on-court interview after the match. '(My) serve got me out of a few tricky spots, but overall, I'd give myself a little pat on the back for that. And happy to get through that match and into the fourth round.

'I was excited for the heat today. Being a Floridian, I was ready for it.'

Both players put 69% of their first serves in play, but Keys won 28 of those 37 points (76%) while Pliskova only won 27 of 48 (56%).

Pegula got off the court even faster, advancing in 66 minutes. At 2-2, the veteran American broke serve on a 14-point game and cruised in the first set.

Selekhmeteva, who entered the tournament ranked No. 101 in the world, put up more of a battle in the second set, but Pegula broke in the sixth and eighth games to quickly retire to the air-conditioned locker room.

'I felt like some things I expected to happen happened and some things I had to adjust to in the first couple games,' Pegula said. 'Her serve wasn't quite as spinny as I thought it was going to be.

'I wanted to stick to a strategy, but you know, sometimes you go out and you feel something different by the way you're hitting the ball, but luckily today, I think things worked out pretty well.'

Keys leads the series with Pegula 2-1 and has won the past two matchups. Their last meeting took place over a year ago in Adelaide, Australia, where Keys won in three sets.

'It's going to be a tough match. Jess is such a great player,' Keys said after learning of the matchup. 'She's always consistently doing so well every single week she plays. She's just so gritty.'

Anisimova has yet to play a clean match, as she served up seven double faults and made 30 unforced errors versus Stearns. Each player had eight break chances, but Stearns only capitalized on two of her opportunities.

Anisimova will play the winner of the match between No. 13 Linda Noskova of the Czech Republic and Xinyu Wang of China.

--Field Level Media