Caroline Wozniacki has reached the final of the US Open after her semi-final opponent, Peng Shuai, was forced to retire midway through their last-four encounter this evening.

The Chinese player made a strong start to the match, twice breaking the 10th seed to leave herself serving for the opening set.

However, the Dane broke back to take the opener to a tie-break, and carried her momentum into the breaker to go a set up, with Peng picking up just a single point.

Wozniacki continued to look the stronger of the two players at the start of the second, breaking Peng to leave herself two games from a place in the final.

Peng brought up a break point to try to get the set back on level terms, but a bout of cramp forced her to call the trainer out, and she was unable to continue after several minutes of treatment.

Wozniacki will face the winner of the match between defending champion Serena Williams and Ekaterina Makarova for the title.