Heather Watson has admitted that she is "disappointed" by her first-round exit at the US Open.

The British number one fell to a straight-sets defeat at the hands of Sorana Cirstea earlier today to fall at the first hurdle of the showpiece competition for the fourth year in a row.

"I couldn't find my serve, I'm not quite sure why, but I've got to look back and improve on that," Watson is quoted as saying by BBC Sport.

"It's disappointing leaving after a first-round loss here, especially after my year and the confidence I've gained. But it's just another week, and I'm going to have a lot more weeks."

Cirstea will face either Eugenie Bouchard or Olga Govortsova in the next round.