Garbine Muguruza has withdrawn from the Rogers Cup after failing to recover from the arm injury that prevented her playing at the Silicon Valley Classic.
Two-time grand slam champion Muguruza was forced to pull out of last week's WTA Tour event in San Jose due to the same issue.
The Spaniard last played at Wimbledon, where she offered a meek defence of her title, and says she needs a longer break in order to return to fitness.
"Unfortunately I am still recovering from my arm injury from last week," Muguruza said in a statement.
"I did everything I could to try and play here but unfortunately I am not ready and need a little bit more time.
"I will miss playing [at the Rogers Cup] and look forward to coming back to Montreal in the future."
The world number seven had been set to face Anastasija Sevastova, who will now instead play lucky loser Monica Puig.