The world No. 2 injured his right wrist while practising Tuesday and withdrew from the tournament on Wednesday.
“I’m extremely disappointed that I am unable to defend my Rogers Cup title this year,” Nadal said in a statement released by Tennis Canada. “I have always loved to play in Canada and had great results in the past.
“After checking with my doctors I will have to stay out of competition for at least two to three weeks.”
Nadal defeated Canada’s Milos Raonic 6-2, 6-2 in last year’s Rogers Cup final in Montreal.
This year’s star-studded field will still include 43 of the world’s top 44 ranked men’s singles players, most notably past champions Novak Djokovic, Roger Federer and Andy Murray along with Raonic.
In Nadal’s absence, Murray moves into the No. 8 seed, giving him a first-round bye.
The CBC will have live TV and online coverage of the semifinals and finals from both the men`s tournament at Rexall Centre and women’s event at Uniprix Stadium in Montreal on Aug. 9 and 10, respectively.