Rafa Nadal has left tennis fans gobsmacked at the US Open after giving up and walking off court in the middle of a rally during his shock loss to Frances Tiafoe.
Tiafoe produced the upset of the US Open so far when he shocked the 22-time grand slam champion in four sets in their fourth-round clash on Monday.
'CAN'T DO THAT': Daniil Medvedev rages at Nick Kyrgios' box
'NEVER SEEN THAT': Nick Kyrgios loses point after illegal act
Tiafoe buried his head in his hands and cried on the court after he shook hands with Nadal, before burying his head in his towel as Nadal walked off and waved to the crowd.
The writing may have been on the wall for Nadal when he gave up on a point in extraordinary scenes in the third set.
Nadal and Tiafoe were locked at one-set apiece with the American up 5-3 in the third when Nadal gave up in the middle of a rally.
Nadal was forced to hit a defensive lob after being moved to the backhand side by Tiafoe, and knew as soon as he hit the ball that he wasn't going to win the point.
Despite his shot going over the net, Nadal turned his back to the court and simply walked over to pick up his towel.
Tiafoe was left with the simplest of winners as spectators in attendance audibly gasped that Nadal had given up.
"That will be the slowest winner hit today," one TV commentator said.
While Nadal was long odds to win the point, many were left gobsmacked that he'd simply walk away rather than fight to the end and make Tiafoe earn it.
Tennis writer Yasmin Syed tweeted: "Maybe the first time in my life I've ever seen Nadal give up on a point? Understandable at that one."
Something's off about Rafa in this match.
— Yushubh Khungar (@KhungarYushubh) September 5, 2022
Same, it looked so odd to see him do that haha
— Mainly Tennis (@mainlytennis) September 5, 2022
Tiafoe is doing Rafa things to Rafa. Never seen Nadal have to give up on points because they're already by him. Gonna be a serious dig now vs the kid.#USOpen
— Anthony Rothman (@AnthonyRothman) September 5, 2022
The American outsider went on with the set to take a 2-1 lead before completing an extraordinary 6-4 4-6 6-4 6-3 upset.
The 24-year-old Tiafoe is the youngest American to reach the quarter-finals since Andy Roddick did so at 24 in 2006.
After Daniil Medvedev's loss to Nick Kyrgios on Sunday, Nadal had the chance to reclaim the World No.1 ranking.
However Carlos Alcaraz and Casper Ruud both now have the opportunity to become first-time World No.1s.
Before the loss, Nadal was 22-0 in grand slam matches in 2022 having won the Australian and French Opens before withdrawing before the semi-finals at Wimbledon.
The Spaniard was 21-1 against Americans since October 2017, which included straight-set wins over Tiafoe in the Australian Open quarter-finals and Madrid third round in 2019.
Tiafoe will face ninth seed Andrey Rublev in the last eight after the Russian scored a 6-4 6-4 6-4 victory over seventh-seeded Brit Cameron Norrie.
Iga Swiatek overcomes stumble to advance
Meanwhile, World No.1 Iga Swiatek has set up a quarter-final showdown with Jessica Pegula after overcoming an early deficit to beat Jule Niemeier.
Pegula was up against two-time Wimbledon champion Petra Kvitova, but she brushed her aside 6-3 6-2 to reach her third major quarter-final of 2022.
Swiatek beat Germany's Niemeier 2-6 6-4 6-0, but is clearly not in the form that brought her 37-straight wins earlier this season.
Swiatek came into the US Open just 4-4 in her last eight matches but she hadn't lost a set at Flushing Meadows until Monday.
Niemeier got the early jump - as she exhorted the crowd to get louder - and gamely tried for another grand slam upset and knocking out No.2 seed Anett Kontaveit at Wimbledon.
Swiatek steadied herself in the second set and hit 10 winners, and she turned the third set into a 6-0 rout.
The World No.1 became the first Polish woman to reach the quarterf-inals at the US Open and is trying to become the first top-seeded woman to win it since Serena Williams in 2014.
"I'm just proud that I didn't lose hope because she was playing really good in the first set," she said on court.
"I'm pretty glad that I used my experience to keep the same kind of level throughout the whole match."
Click here to sign up to our newsletter for all the latest and breaking stories from Australia and around the world.