MELBOURNE, Australia -- Canadian Vasek Pospisil has withdrawn from his scheduled third-round match at the Australian Open against No. 8-seeded Stanislas Wawrinka with a back injury, giving the Swiss player a walkover on Friday.

No. 28 Pospisil was bothered with the injury during his second-round win Wednesday over Australian Matt Ebden, needing treatment from physiotherapists during the match. He retired with the same injury during his semifinal against Wawrinka in the Chennai Open in India earlier in the month.

Wawrinka has had a relatively easy run to the fourth round. He didn't have to complete his first-round match Monday, leading 6-4, 4-1 when Andrey Golubez of Kazakhstan retired with a calf injury.