Emma Raducanu reached the second round of the Washington Open after surviving a first-set wobble to beat Marta Kostyuk on Tuesday.
On the day it was announced Raducanu was part of Great Britain's Billie Jean King Cup team, she started her quest to become the British number one with a 7-6 (7-4) 6-4 win.
But the former US Open champion was forced to come from behind in the first set as Kostyuk grabbed the first break of the match in the third game.
Raducanu, however, responded with a break of her own in the following game before edging the tie-break, taking the first set in one hour and 10 minutes.
But from there, Raducanu took control as she got the better of the seventh seed's serve to surge into a 3-0 lead in the second set.
Kostyuk broke back to put the pressure on, but Raducanu remained composed to see out the win, sealing the victory against the serve after her opponent sent a volley wide of the mark.
The world number 27 is the highest-ranked player Raducanu has beaten since May, when she defeated world number 17 Daria Kasatkina in Strasbourg.
"Extremely good win," Raducanu said in her on-court interview. "Playing Marta in the first round is extremely difficult, and we've always had some tough matches.
"I'm happy with the way I fought through the first set and, in the second, stayed tough when I needed to."
