Canadian Vasek Pospisil has retired from the US Open with a back injury according to TSN's Mark Masters.

Pospisil exited after the first set of his match with Fernando Verdasco after a brief discussion with the trainer. 

The 27-year-old started the season outside the top 130, but got back into the top 80. He won the Busan Challenger in Korea, taking home 120 ATP points. 

Pospisil is Canada's third-highest ranked player behind Milos Raonic and Denis Shapovalov.