New York, United States, 31 August 2019 | Darren Walton (AAP)

Ash Barty passed the sternest test yet of her US Open title credentials to equal her best-ever run in New York and edge ever closer to a blockbuster quarterfinal with Serena Williams.

Barty delivered a serving masterclass class to reach the last 16 for the second straight year with a clinical 7-5 6-3 victory over rising Greek Maria Sakkari on Friday.

Sakkari, seeded 30th, had beaten Barty last year in Indian Wells but Australia’s world No.2 played the match on her terms from the outset.

The French Open champion fired down 10 aces and dropped serve only once while breaking Sakkari four times during the 87-minute work-out on Louis Armstrong Stadium.

“This is an incredible court. New York is an incredible city and last year I felt like an adopted American playing with Coco (Vandeweghe) in the doubles, so I’m glad you haven’t forgotten,” Barty said after enjoying clear crowd favouritism during the match.

“Maria is an incredible competitor, a great mover around the court and plays her best tennis when she’s on the move and so it was important for me to try and dictate without going into her patterns.

“It’s tricky to play a friend but I was really happy with the way I able to close out those two sets.”

Barty will face either China’s 18th seed Qiang Wang or unseeded Frenchwoman Fiona Ferro next on Sunday, with the winner likely strike Williams in the last eight.

Continuing her relentless quest for a record-equalling 24th Grand Slam singles title, eighth seed Williams swatted aside Karolina Muchova 6-3 6-2 in her third-round match.

Barty and Williams were also slated to collide in the Wimbledon quarterfinals, only for Australia’s then world No.1 to suffer a shock fourth-round loss to unseeded American Alison Riske.

Later on Friday, Barty teamed up with Victoria Azarenka to beat Margarita Gasparyan and Monica Niculescu 4-6 6-1 6-1 in the doubles.

Ajla Tomljanovic was another Aussie doubles winner, alongside Sakkari, while Ellen Perez and American Danielle Collins upset sixth seeds Sam Stosur and Shuai Zhang 1-6 6-4 6-4.

Monique Adamczak and Jessica Moore also saw their doubles hopes end alongside Xinyun Han and Giuliana Olmos respectively.