The Briton has pulled out of the event, due to be held at the Uniprix Stadium in Montreal, because of the ongoing hip issue which marred his recent Wimbledon campaign.

His withdrawal means he could now lose his place at the top of the world rankings to Nadal, who only needs to reach the semi-finals in Canada to take over at the summit of world tennis.

Double Wimbledon and Olympic champion Sir Andy also remains a doubt for the US Open, which begins on August 28 in New York City.

"I am sad to be missing the tournament in Montreal because I have many great memories from my time in Canada," Murray said in a statement released by Tennis Canada.

"I am doing everything I can to return as quickly as possible."

Other notable names have also withdrawn from Montreal including Croatia's Wimbledon finalist Marin Cilic, who is still suffering from an abductor injury.

Three-time grand slam champion Stan Wawrinka has also been ruled out for the remainder of the 2017 season because of a knee injury, joining Serbia's defending champion and 12-time grand slam winner Novak Djokovic on the sidelines.

Nadal is the number one seed in Montreal while Switzerland's Roger Federer is second with both players receiving byes in round one.

The duo have won four of the five Association of Tennis Professionals World Tour Masters 1000 events held this year with the Swiss star victorious at Indian Wells and Miami while Nadal prevailed in Monte Carlo and Madrid. 

Others set to compete in Montreal include third seed Dominic Thiem of Austria, home favourite Milos Raonic and Japan's Kei Nishikori, who was last year's runner-up.

Karolína Plíšková will be playing in her first event since becoming world number one last month at the women's version of the Rogers Cup, due to be played at the Aviva Centre in Toronto.

The Czech player was confirmed as the new top ranked player in the latest Women's Tennis Association rankings.

The 25-year-old, who reached the semi-finals of the French Open earlier this year, was knocked out at the second round stage of Wimbledon but gained enough points to climb two places in the rankings and replace Germany's Angelique Kerber.

All of the tournament's top eight seeds have byes.

They include Plíšková, Romania's Simona Halep, Kerber, Spain's Wimbledon champion Garbiñe Muguruza, Elina Svitolina of Ukraine, Denmark's Caroline Wozniacki, Great Britain's Johanna Konta and Russian Svetlana Kuznetsova.

In last year's Rogers Cup final, Halep defeated Madison Keys of the United States 7-6, 6-3.

First round action in both the men's and women's events is due to begin tomorrow.