Wimbledon's Laura Robson is out of the US Open after losing 6-4 6-4 to the defending champion Sam Stosur.
Robson, 18, was aiming to become the first British woman to reach a grand slam quarter-final for 28 years but the Australian was too strong, winning in 98 minutes.
After knocking out former grand slam winners Kim Clijsters and Li Na en route to the fourth round, Robson started well against Stosur and broke the reigning champion's serve, only to be broken back immediately.
However, Robson went on to miss break point chances at crucial stages and Stosur went on to win the decisive set on Robson's serve.
Meanwhile, Ross Hutchins and doubles partner Colin Fleming lost their third round tie agains the US pairing of Christian Harrison and Ryan Harrison 3-6 4-6.