Caroline Wozniacki through to US Open second round

Caroline Wozniacki is through to the second round of the US Open after Magdalena Rybarikova was forced to retire in the final set.

Despite breezing through the first set 6-1, the Dane was put through her paces against Rybarikova, who took the second 6-3 before succumbing to injury in the third with Wozniacki up 2-0.

The Slovakian was struggled with her movement throughout and eventually had to withdraw with a back problem.

Wozniacki will meet Aliaksandra Sasnovich in the next round.