An emotional Andy Murray continued to make encouraging strides on his comeback from hip surgery as he booked his place in the quarter-finals of the Citi Open in Washington.
The 31-year-old Scot, who withdrew from Wimbledon after deciding he was not quite ready to compete, showed impressive reserves of fitness to see off Romania's Marius Copil 6-7 (5/7) 6-3 7-6 (7/4).
The match in the US capital lasted three hours and two minutes and finished just after 0300 local time, and Murray buried his head in his towel at the conclusion of the match, apparently sobbing.
Murray hit out at the scheduling of his third-round match, suggesting he may even pull out rather than risk putting his body through such an ordeal so soon in his comeback.
He told reporters: "I don't think it's reasonable and I'm disappointed in that. I know that the weather's tricky for the scheduling. But it's a very difficult position to be in when you're coming back from such a long lay-off.
"Finishing matches at 3am is not good. It's not good for the players, not good, I don't think, for anyone involved in the event. Not good for fans, not good for TV, nobody."
It was the latest finish in the 50-year history of the tournament, which this year has been blighted by rain.
Asked about why he had been reduced to tears after the match, Murray replied: "(It was) just the emotions coming at the end of an extremely long day and a long match."
Murray is 10/1 for the US Open with Sky Bet but before that will next face Australia's Alex de Minaur in the last eight on Friday evening.
Top seed Alexander Zverev is also into the last eight after a 6-3 7-5 victory over his brother Mischa. The German will play Kei Nishikori in the quarter-finals after he emerged as a 7-6 (7/1) 6-3 winner against Denis Shapovalov.
David Goffin broke little sweat in beating Frances Tiafoe 6-0 6-3 and the Belgian will face Stefanos Tsitsipas after the Greek got the better of James Duckworth 6-3 6-4. Denis Kudla was a surprise 7-5 6-7 (6/8) 7-6 (7/5) winner over Lucas Pouille to set up a last-eight clash against Andrey Rublev, who won 6-3 6-2 against Noah Rubin.
Juan Martin del Potro made a safe passage into the semi-finals of the Abierto Mexicano in Los Cabos.
The Argentinian beat Egor Gerasimov 6-1 6-1 and the top seed will face Damir Dzumhur in the last four after the Bosnian triumphed 6-2 6-3 against Michael Mmoh.
Second seed Fabio Fognini beat Yoshihito Nishioka 6-2 6-2 and he will play Britain's Cameron Norrie, who won 6-4 6-4 against fourth seed Adrian Mannarino of France.
Elsewhere, Maximilian Marterer was knocked out of the quarter-finals of the Generali Open by qualifier Denis Istomin. Marterer, the highest seed remaining in the draw, was beaten 6-3 6-3 by Uzbekistan's Istomin in Kitzbuhel.
Martin Klizan won 4-6 7-6 (8/6) 6-2 against Dusan Lajovic, Jaume Munar was a 7-6 (7/3) 6-3 winner over Taro Daniel while Nicolas Jarry saw off Matteo Berrettini 7-5 6-3.
In the women's Mubadala Silicon Valley Classic, Heather Watson gave Venus Williams a battle in San Jose but eventually went down in three sets.
Number three seed Williams dropped her second service game but immediately broke back.
With the set finely poised at 5-4, Watson lost two points on the bounce as the seven-time Grand Slam winner took an early advantage.
Watson broke Williams in the third game of the second set to open up a 3-1 lead.
Williams drew things level at 4-4 with a break of serve, but Watson restored the lead when she broke back for 5-4.
The Briton then wrapped up the set in 43 minutes, winning it 6-4 and taking the match into a decider.
Williams closed the match out in rapid fashion, dishing out a bagel to the Briton.
The fourth game of the final set was a 15-point epic, with the American closing out on her fifth break point.
A third break of serve in the set saw Watson defeated, while Williams goes on to play Maria Sakkari.
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