Emma Raducanu dug deep to battle past Colombian Camila Osorio into the quarter-finals of the Citi Open in a match played out during sweltering conditions in Washington.
The British No 1 had secured a first win of the North American hard-court season through a two-and-a-half hour battle over Louisa Chirico and was looking to build some momentum.
Defending US Open champion Raducanu, the tournament’s second seed, started brightly to move 3-0 ahead in the first set following an early break and hold.
After then finding herself trailing 4-2, Osorio, the world No 67, recovered with two breaks of her own to lead 5-4.
Raducanu, though, rallied again to save two set points in the 10th game and level things up as the opening set went on to a tie-break.
After moving 2-0 ahead with a mini-break, Raducanu’s serve faltered once more as Osorio led 5-3.
However, the British world No 10 then showed great resilience to level up before forcing a set point, which she secured with another break.
Raducanu moved 4-2 ahead in the second set and looked in control, but once again Osorio responded to level at 4-4 before both players lost serve.
Raducanu needed a medical time-out for treatment on blisters on her racquet hand, which proved so costly at the Australian Open, but returned to hold as the set moved into another tie-break.
The 19-year-old continued to dig deep as she dominated from the baseline to edge 5-3 ahead, before sealing her first match point as Osorio sent a service return wide, winning 7-6 (7-5) 7-6 (7-4).
“I think I died about three times in that match and I came back – honestly, I don’t know how,” Raducanu said in her post-match comments on court.
“Camila is such a battler. I was working so hard for every single point.
“When she comes back, the dynamic of the match changes a bit, so I am just really pleased to have got through that one.”
Both players had received medical time-outs at stages during the match, Osorio for a blister on her big toe midway through the second set.
Of her own hand issues, Raducanu said: “At the beginning of the match I was alright, but then throughout the match my skin was just ripping off – it was pretty raw and open.”
Raducanu will go on to play Russian Liudmila Samsonova for a place in the last four.
The British No 1 said: “She is a big ball striker and has the ability to take the game out of your hands, so for me it is just about recovery as best as I can for tomorrow.
“Both of us are going to be feeling it, and it is a matter of who is going to stay tough.”
Evans outlasts Fritz
In the ATP event, British men’s No 2 Dan Evans progressed to the quarter-finals after Taylor Fritz was unable to continue during the third set because of the humid conditions at Rock Creek Park.
American third-seed Fritz had won the opening set before Evans, who defeated fellow Briton Kyle Edmund in the last round, rallied to take the second on a tie-break.
As Fritz, the world No 13, continued to battle on, Evans moved 4-1 ahead.
At the end of the fifth game, Fritz called for medical assistance and then decided to withdraw, as Evans progressed 3-6 7-6 (8-6) 4-1. Evans will next play Yoshihito Nishioka of Japan.