Tennis favourite Grigor Dimitrov has been forced to retire in brutal circumstances after leading Austrian Dominic Thiem at the Winston-Salem Open.
Dimitrov had blown away Thiem 6-0 in the opening set of the US Open build-up tournament, but appeared to feel discomfort heading into the second.
Thiem, recovering from a long-term wrist injury, lifted his game in the second and was leading 4-2 as Dimitrov called for the trainer.
It appeared the Bulgarian No.1 seed was struggling to breathe on court.
Ahead of his service game, Dimitrov dropped the ball and approached the net to signal his retirement.
The former World No.3 bent over in pain as Thiem met him and they embraced in a good show of sportsmanship.
Dimitrov's retirement from the ATP 250 event is a concern considering the US Open is only five days away.
Tennis fans reacted with sadness after watching Dimitrov limp towards the end only days before the final grand slam of the year.
Dominic Thiem advances after tennis return
On the flip side, it was important for Thiem to advance and garner more match practice after he faced more than a year away from the game.
Thiem, a former World No.3 and US Open winner, has slipped to World No.231 after sitting out from the tour after a long-term wrist injury.
The 2020 US Open winner was granted a wildcard to Flushing Meadows this year.
Thiem was unable to defend his US Open crowd last year due to his wrist injury.
Before his first round victory, Thiem hadn't won a match on a hard court since March 2021.
Elsewhere, Aussie Jason Kubler is into the last 16 of the ATP event in North Carolina after defeating South Korea's Kwon Soon-woo.
Qualifer Kubler, ranked 116 in the world, needed one hour 41 minutes to see off the world No.81.
The 29-year-old from Brisbane won 81 per cent of points on his first serve, fought off two break points, and broke three times himself to set up a meeting with Laslo Djere.
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