Andy Murray in tears after gruelling victory in Citi Open

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.

Andy Murray can't hide his emotion after a tough victory over Marius Copil. Picture: AP

He will next face Australia’s Alex de Minaur in the last eight on Friday evening.

Copil proved a testing opponent, breaking back when Murray appeared set to move clear in the decider.

Murray, who underwent hip surgery in January, reached this stage with wins over Mackenzie McDonald and fellow Briton Kyle Edmund, and now faces world number 72 De Minaur for a place in the semi-finals.