Britain’s Emma Raducanu mentioned she wanted a “monumental effort” to beat Colombia’s Camila Osorio and attain the Washington Open quarter-finals.
Raducanu, who will begin the defence of her US Open title this month, received 7-6 (7-5) 7-6 (7-4) in two hours 50 minutes.
“It simply offers you a variety of confidence coming by means of a match like that,” mentioned the British primary.
Compatriot Dan Evans progressed as American Taylor Fritz retired.
In sizzling and humid situations, Raducanu and Osorio required medical timeouts.
“For me it was a reasonably monumental effort to actually get by means of that,” mentioned Raducanu.
“There have been many moments in each units the place you wish to go for the simple choice of attempting to complete the purpose early, however I am simply actually happy and happy with how I dug in when it actually mattered.”
Raducanu will play Russia’s Liudmila Samsonova within the final eight.
Evans, who saved match level however was main 3-6 7-6 (8-6) 4-1 when Fritz withdrew, faces Yoshihito Nishioka of Japan within the quarter-finals.
Fritz mentioned he felt “embarrassed” at not having the ability to end the match, however that he had been carrying a protecting boot since Wimbledon final month due to a foot harm.
“I continually felt like I used to be going to move out, my imaginative and prescient was going fuzzy,” he mentioned on social media.
“The one factor that may actually put together me for taking part in in these situations… is taking part in in these situations, one thing I simply have not been capable of do whereas nursing my foot.
“Now that my foot feels higher I can lastly put within the on-court work and be ready for the remainder of the yr. Sorry if I nervous anybody.”