'Probably would have won': In-form American retires hurt with 'worst pain ever'

Ben Shelton was reduced to tears as he walked off the court injured. (Getty/Sarah Stier)

Playing arguably the best tennis of his young career, American hopeful Ben Shelton placed a towel over his head in tears after being forced to retire at the US Open with a shoulder injury.

Shelton, who recently won his maiden Masters 1000 title in Toronto, was physically struggling in the fourth set of his match against tricky Frenchman Adrian Mannarino.

Shop with a 15% storewide discount code: SERVE15 - excludes clearance items, machines, court equipment and gift cards at www.tennisdirect.com.au

It came after he won an incredible set point in the third, at the expense of falling to the ground, forcing him to take a medical timeout.

Shelton turned to his box and said it was the "worst pain I've ever felt in my life".

Then, locked at two sets apiece, Shelton couldn't hold back tears as he slumped in his chair in discomfort, as the tournament physio tried to treat the issue.

The camera turned to his father and coach, Bryan, who made hand signals to his son, directing him to cut the match short.

Play USA with Lachlan Puyol goes inside the journey of many Aussies going down the college pathway as an entry point to professional tennis – The First Serve Podcasts.

"It hurts," 22-year-old Shelton admitted in his press conference. "But you won't hear me pouting over here about how bad things are. I have a lot of blessings."

For the first time in his career, the sixth seed pulled the pin mid-match, which ends his chances of becoming the first American man to win the US Open since Andy Roddick in 2003.

"When he started to have pain, he was leading in the match; he honestly probably would have won that match," said Mannarino in front of a stunned crowd on Louis Armstrong Stadium.

"It's very unfortunate for him and lucky for me."

Mannarino, who defeated Aussie Jordan Thompson in the second round, will face 20th seed Jiří Lehečka for a spot in the quarter-finals.

Tennis Coaches Australia, coaches supporting coaches, your voice, your network, stronger together. For all enquiries and membership details, go to tenniscoachesaustralia.au