Tadej Pogacar returns to competitive action for the first time since his Tour de France triumph looking for wins in the Grand Prix races in Quebec and Montreal.
The UAE team leader pulled out of the Paris Olympics citing tiredness after winning a third Tour title in July.
The Slovenian will be favourite to succeed Belgian Arnaud De Lie and Britain's Adam Yates, winners in Quebec and Montreal respectively last year.
The two races are circuits with 16 laps in Quebec on Friday and 17 in Montreal on Sunday, and with extremely demanding repetitive climbs.
Pogacar is building towards the world championships in Zurich from September 21 to 29.
He is aiming for a hat-trick of the world title, the Giro d'Italia and Tour de France, only held by two men, Ireland's Stephen Roche and Belgian Eddy Merckx.
"I took advantage of the summer at home, I went to the beach. I hadn't done that for a few years. I made the right decision," said the 25-year-old.
"I trained well. In general, my recovery races after a long break always go well."
Rivals include De Lie who achieved his first World Tour success last year, Frenchman Julian Alaphilippe and Australian Michael Matthews.
The only two World Tour races on the American continent will also be a rehearsal for the 2026 world championships in Montreal.