Circumstances will likely be robust on the remaining Grand Slam of the season, which takes place within the New York summer season and can proceed to see matches performed in whiteout situations.
That is a type of instances. Temperatures hit 35C at Flushing Meadows as Dart confronted Kostuk in a swirl of afternoon warmth.
Consequently, each gamers struggled to compose themselves in a disorganized match that lacked high quality.
Double faults adopted from every server, together with Kostyuk at one set level within the tie-break, and one other from Dart handed him the primary break of the second set.
Wild returning was one other facet of the match that was significantly troublesome to trace within the first set.
After the US Open, Dart will leapfrog Emma Raducanu to turn out to be the British No. 2 as she breaks into the world's prime 70 for the primary time on the again of a first-round win over France's Chloe Paquet.
Beating Kostyuk would have moved Dart into the highest 60 and secured one of many largest wins of his profession within the rankings.
She made a pointy begin however was not scientific sufficient in a poor first set.
A questionable second serve left Dart's opponents pouncing.
Dart regarded near tears as she returned to the court docket and gestured to her crew, led by her mom Susie, who has been teaching her in New York.
Phrases of reassurance couldn't assist Dart get again into her rhythm, and the combat was drained from her as Kostyuk completed off a success that ended extra comfortably than it ought to have.