Second seed Dominic Thiem edged a first-set tiebreak before turning up the heat to romp into the US Open quarterfinals with a resounding 7-6(4) 6-1 6-1 victory over Canadian youngster Felix Augur-Aliassime at Arthur Ashe Stadium on Monday.
Top seed Novak Djokovic's disqualification on Sunday for striking a line judge with a ball has left Thiem as one of the favourites and the Austrian gave a composed performance to reach the last eight in New York for the second time in his career.
Serena Williams booked a place in the quarterfinals with a hard-fought, three-set win over 15th seed Maria Sakkari.
Williams required two hours and 28 minutes to defeat the 25-year-old Greek player 6-3, 6-7 (6/8), 6-3.
Tsvetana Pironkova reached the last eight defeating France's Alize Cornet in three sets.
The unranked Bulgarian, who only returned to tennis this year following a three-year absence from the circuit, secured her last eight berth with a 6-4, 6-7 (5/7), 6-3 victory at the Louis Armstrong Stadium. Pironkova will now face third seed Serena Williams in the quarterfinals on Wednesday.
Next up for the 26-year-old is a quarterfinal clash with Australian youngster Alex de Minaur, who he has beaten in both of their previous meetings, including in the opening round at Flushing Meadows three years ago.
Daniil Medvedev advanced into the quarterfinals with a dominant 6-4 6-1 6-0 win over a listless Frances Tiafoe.
The win marked Williams's 100th win on the famous Ashe court and set up her 53rd quarterfinal appearance at a tennis major.
Williams is seeking a 24th Slam that would equal Margaret Court's record for the most women's Grand Slam singles titles.
Tsvetana Pironkova reached the quarterfinals, defeating France's Alize Cornet in three sets.
The unranked Bulgarian, who only returned to tennis this year following a three-year absence from the circuit, secured her last eight berth with a 6-4, 6-7 (5/7), 6-3 victory at the Louis Armstrong Stadium.
"It's absolutely unreal, I really can't believe it," Pironkova said.
In New York she has claimed a couple of seeded scalps, defeating 10th seed Garbine Muguruza in the second round before knocking out 18th seed Donna Vekic in the third round.
Second seed Sofia Kenin of the United States was sent crashing out, beaten in straight sets by Elise Mertens of Belgium. Kenin, the highest seeded player left in the tournament and winner of the 2020 Australian Open, was bundled out of the last 16 6-3, 6-3, in 1hr 14 mins by Mertens.
Mertens, the 16th seed, will now play Victoria Azarenka of Belarus in the quarterfinals.
Unseeded Azarenka came from a set down to oust 20th seed Karolina Muchova 5-7, 6-1, 6-4.