Kyle Edmund retires from French Open second-round match against Pablo Cuevas
Kyle Edmund is out of the French Open after retiring during his second-round match against Uruguayan Pablo Cuevas because of a left knee injury.
The British number one, 24, trailed 7-6 (7-3) 6-3 2-1 when he shook hands with world number 47 Cuevas.
"You don't want to stop because you feel like you're quitting, but sometimes you have to," he said.
Edmund said he is managing a long-term problem but believes he does not need surgery and will be fit for Wimbledon.
"There have been a few times this year I have carried on and nothing got better and sometimes a bit worse," he added.
"It won't need surgery right now. If it did I wouldn't be playing, I'd get it sorted straight away rather than delaying the inevitable."
The Yorkshireman says he thinks he will be ready for the grass-court season, which is set to begin for him at Queen's on 17 June and continue at Wimbledon from 1 July.
"The only way I won't play on the grass is if it gets worse through training from now to the first match. I definitely anticipate I will play," he told BBC Sport.
Edmund's exit at Roland Garros leaves Johanna Konta as the only Briton left in the singles.
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A struggle from the start
Edmund was bidding to reach the last 32 of the French Open for the third successive year, having ended a five-match losing streak on clay this year with a gutsy five-set win over France's Jeremy Chardy in the opening round.
But Edmund never looked comfortable from the start against 33-year-old Cuevas, a clay-court specialist who has won all of his six ATP Tour singles titles on the surface.
After losing his opening service game of the match, Edmund fought back to level the first set at 4-4 before Cuevas ran away with the tie-break.
Cuevas caused problems with his dominant backhand as Edmund struggled to unload his favoured forehand, the Briton winning just four points on his way to losing the final four games of the second set.
That left Edmund needing to do something he had never done in his career - win from two sets down.
From this position he had lost 13 previous matches and another exit followed when he shook hands with Cuevas, who will face Austrian fourth seed Dominic Thiem in the last 32.
Analysis - 'a bigger issue than we thought'
BBC Sport tennis correspondent Russell Fuller at Roland Garros
It was in Paris at the end of last October that Kyle Edmund's knee problem first came to light.
An MRI scan revealed fluid behind the left knee and he decided to give his last tournament of the year a miss.
It was a bigger issue than we first thought: hindering him significantly in Australia in January, and - as has now become apparent - intermittently over the past few months.
Edmund says the "complex" problem fluctuates. Surgery is not yet being considered, he says, but it could become quite debilitating if his body struggles to withstand four-hour matches of the type played with Jeremy Chardy in the first round.
Difficult day for Britons in doubles
Britain's Dan Evans and Cameron Norrie were beaten by fourth seeds Robin Haase and Frederik Nielsen in the second round of the men's doubles, while Ken and Neal Skupski were also knocked out after losing in straight sets to Mike and Bob Bryan, the fourth seeds.
Heather Watson and her partner Tatjana Maria of Germany went out in the first round of the women's doubles, losing 6-3 6-2 to sixth seeds Elise Mertens and Aryna Sabalenka.
But Joe Salisbury progressed to the second round of the men's doubles along with American partner Rajeev Ram when opponents Damir Dzumhur and Filip Krajinovic were forced to retire.