British number one Katie Boulter showcased her fighting spirit to book her place in the second round of the US Open.

Boulter, seeded 31st in the final grand slam of the year, joined compatriot Harriet Dart in the next stage after a 5-7 6-2 6-1 win over Aliaksandra Sasnovich.

The win was far more testing than the scoreline suggests as she endured a battle in sweltering New York conditions.

She started brightly, winning the opening two matches, before the Belarusian started causing problems with a strong forehand weapon.

Sasnovich was able to turn the first set around, breaking at 5-5 to assume control.

But Boulter dug deep and again started the second set well, crusing into a 3-0 lead which allowed her to send it to a decider.

The contest was still not over, though, as the Briton had to fend off four break points in the opening game.

However, she took control of her destiny with a run of five successive games to make it through to the second round – and a match against Jessica Bouzas Maneiro or Petra Martic.