Russia's Daniil Medvedev defeated a lower leg damage at that point battled off a match point to progress to the second round of the Washington Open on Monday.
Medvedev bent his lower leg late in the third set and battled off a match point against Reilly Opelka before he won 6-7(8) 6-3 7-6(6) to move into a moment round conflict with American Steve Johnson.
The men's draw endured a minor blow when John Isner, who won the Atlanta title a week ago and has been beaten three times in the last in Washington in 2007, 2013 and 2015, needed to pull back from the competition with knee damage.
"Disillusioned to have pulled back from the @CitiOpen this year," Isner posted on Twitter. "Tragically, I'm recently not exactly sufficiently fit for it this year. I'll be back!"
In other first-round men's activity, American Donald Young beat countryman Tim Smyczek 4 6-3 6-4, to set up a moment round conflict with World No 9 Kei Nishikori.
World No 7 Dominic Thiem, the best seed, is because of play on Tuesday, while Argentina's previous U.S. Open champion Juan Martin del Potro is additionally on the court.
Ladies' third seed Lauren Davis was agitated with Aryna Sabalenka 7-5 6-3 on Monday, while previous No 1 Jelena Jankovic resigned while trailing Oceane Dodin 2-0 in the third set.
German fourth seed Julia Goerges crushed Francoise Abanda 6-4 6-4.
Top seeded Simona Halep will confront American Sloane Stephens, who won the competition in 2015 on Tuesday.