Boulter has leapt up the rankings after a strong 18 months where she has stayed fit and caused problems for opponents with her powerful game.

Now, she is aiming to break another ceiling by reaching the second week of a Grand Slam tournament for the first time.

But coming into the US Open, Boulter admitted she was not as prepared as she might have been for the hard courts because of her participation in the Paris Olympics which was played on clay.

That experience meant she played just three completed matches on hard courts before starting her campaign at Flushing Meadows.

“There are always going to be moments where you’re arriving late at a tournament or rushing around or changing surface,” said Boulter, who reached the third round last year.

“Those things can definitely throw you off. But it is important to stay realistic in these moments.

“I’ve done that great in the last few weeks and that helped me win today.”

In contrast, Sasnovich was match sharp, having come through qualifying without dropping a set.

The difference showed in an opening set where Boulter struggled to land first serves and paid the price as she was broken three times, undoing the good work she had done to twice take Sasnovich’s unorthodox serve.

The Belarusian’s eye-catching motion, striking a pose like a flamenco dancer with her serving arm aloft before tossing the ball, looks awkward and lacked ferocity.

Boulter was able to break four times which, in conjunction with more solidity in her service games, allowed the Briton to confidently roll through the next two sets.

Boulter goes on to play Spain’s Jessica Bouzas Maneiro in the second round on Thursday.