WASHINGTON: Britain's Emma Raducanu beat Colombia's Camila Osorio to advance to the Washington Open quarter-finals on Thursday.
In two hours and fifty minutes, Raducanu triumphed 7-6 (7-5) 7-6 (7-4) to begin the defence of her US Open championship.
"It just gives you a lot of confidence coming through a match like that. For me, it was a pretty monumental effort to really get through that," said Raducanu.
"There were many moments in both sets where you want to go for the easy option of trying to finish the point early, but I'm just really pleased and proud of how I dug in when it really mattered."
Raducanu will clash with Russia's Liudmila Samsonova in the last eight of the event.
Meanwhile, compatriot Dan Evans advanced after his American Taylor Fritz retired,
When Fritz withdrew, Evans Evans had a 3-6 7-6 (8-6) 4-1 lead at the time and will next face Yoshihito Nishioka of Japan in the quarterfinals.