Croatian fifth seed Marin Cilic has been ousted in the ongoing US Open by Argentine 29th seed Diego Schwartzman 4-6, 7-5, 7-5, 6-4.
Canadian teen, Denis Shapovalov, also became the youngest man since 1989 to progress into the US Open last 16.
Cilic, the 2014 US Open champion had been sidelined since a Wimbledon runner-up showing by an adductor strain.
“(The injury) played a quite significant part, and just being injured and not being able to keep that good form.
“I was struggling with my shots and my serve was off,”Cilic said.
His exit ensured a first-time Slam finalist will come from his draw half, which now lacks a top-10 player.
“Everyone is improving,” Cilic said. “And you have a lot of youngsters coming up that are playing better.”
No one proved that better than Shapovalov, the 18-year-old Israeli-born world number 69 who advanced when Britain’s Kyle Edmund retired with a neck injury with the Canadian leading 3-6, 6-3, 6-3, 1-0.
Before this feat , it was 17-year-old Michael Chang 28 years ago had a younger player cracked the fourth round in New York.
And no qualifier had reached the last 16 since Gilles Muller in 2008.
“It’s never great to win this way. Hopefully it’s nothing too serious,” said Shapovalov. “It’s very unfortunate but at the same time I’m happy to be in the fourth round.”
Shapovalov will play for a quarter-final berth against Spanish 12th seed Pablo Carreno Busta, who ousted French qualifier Nicolas Mahut 6-3, 6-4, 6-3.
Schwartzman, who improved to 2-13 against top-10 foes, next meets French 16th seed Lucas Pouille, who defeated Kazakh qualifier Mikhail Kukushkin 2-6, 6-3, 6-4, 6-4.
Spanish third-seeded Garbine Muguruza wasted no time in dispatching Slovakian 31st seed Magdalena Rybarikova 6-1, 6-1 in one hour and two minutes to continue her best US Open run and take command of the fight for women’s world number one.
She eliminated Venus Williams and already ousted second-ranked Simona Halep from the top spot chase. Only current number one Karolina Pliskova and fourth-seeded Elina Svitolina can deny her reaching the top for the first time.
— US Open Tennis (@usopen) September 1, 2017
Awaiting Muguruza next is Czech 13th seed Petra Kvitova, who defeated French 18th seed Caroline Garcia 6-0, 6-4.
Kvitova, the 2011 and 2014 Wimbledon champion, enjoyed playing in Arthur Ashe Stadium after needing major surgery following a knife attack by a home intruder last December.
Oldest progresses to round of 16
Meanwhile, Italy’s Paolo Lorenzi became the oldest player in the Open Era to reach a Grand Slam last 16 for the first time by defeating countryman Thomas Fabbiano 6-2, 6-4, 6-4.
The night feature on Ashe pits five-time Grand Slam champion Maria Sharapova against 139th-ranked US teen wildcard Sofia Kenin.