Jannik Sinner was Saturday braced to capitalize on the shock US Open exits of title rivals Novak Djokovic and Carlos Alcaraz when he faces Australia's Christopher O'Connell for a last-16 place.
World number one and Australian Open champion Sinner takes on his 87th-ranked opponent a day after four-time champion Djokovic was sent spinning to his earliest loss in New York in 18 years by Alexei Popyrin.
One day earlier, 2022 winner Alcaraz was defeated in the second round by Dutch journeyman Botic van de Zandschulp.
Italian 23-year-old Sinner arrived in New York under a cloud after it was announced he had failed two drugs tests in March but had been cleared of any wrongdoing.
However, he has shrugged off that controversy as he attempts to reach the last 16 for a fourth successive year.
O'Connell, meanwhile, has never made the fourth round of a Slam and was once so disenchanted with the sport that he quit to work as a boat cleaner in Sydney before opting to recharge his tennis career.
"He's a silent assassin, a quiet achiever," said his Australian teammate Jordan Thompson who was also in action later Saturday.
O'Connell defeated Sinner in their first meeting in Atlanta in 2021 before the Italian swept to victory when they clashed again in Miami earlier this year.
With Djokovic and Alcaraz heading home to Europe, Daniil Medvedev is the only former champion left in the draw.
The often eccentric Russian, seeded four, faces Flavio Cobolli, the world number 31, one of three Italians in third round action.
Medvedev famously shattered Djokovic's bid for a rare calendar Grand Slam when he captured the 2021 title in New York.
This year he was runner-up to Sinner at the Australian Open and made the semis-finals of Wimbledon but is without a tour title since winning the Rome Masters in May last year.
Women's world number one and 2022 champion Iga Swiatek dropped one game and secured a season-leading 55th win of 2024 by routing Ena Shibahara on Thursday.
On Saturday, she takes on 33-year-old Anastasia Pavlyunchenkova, who will have revenge on her mind after suffering a 6-0, 6-0 blowout when she met Swiatek in their only other previous meeting on the Rome clay last year.
Pavlyunchenkova is a vastly experienced Grand Slam campaigner, making the 2019 French Open final as well as seven other quarter-final appearances.
One of those came at the US Open in 2011 where she was stopped by Serena Williams.
Meanwhile, in early third round action, 2023 semi-finalist Karolina Muchova, who knocked out two-time champion Naomi Osaka in the second round, cruised into the last 16 by beating Anastasia Potapova 6-4, 6-2.
French Open and Wimbledon runner-up Jasmine Paolini, the fifth-seeded Italian, beat Yulia Putintseva 6-3, 6-4.
Paolini has now made the fourth round of all four Slams this year having previously never got beyond the second round in 16 attempts.
US sixth seed Jessica Pegula made the last 16 for a third successive season by defeating Jessica Bouzas Maneiro 6-3, 6-3.
Czech Republic's Tomas Machac, ranked 39, reached the fourth round of a major for the first time by seeing off Belgian veteran David Goffin 6-3, 6-1, 6-2.
