Defending champion Samantha Stosur is safely through to the fourth round of the US Open following a straight-sets victory over Varvara Lepchenko.
Stosur was broken on her first service game by the 31st seed before cancelling it out instantly.
The Australian then failed to take three break points as the first set went to a tie-break.
With both players struggling to hold serve, it was Stosur who eventually came out 7-5 to take the initiative.
It was a far simpler affair in the second as the seventh seed came through 6-2 to set up a last-16 tie against Laura Robson.
