Roger Federer was unable to mount a challenge in the second set
The Wimbledon champion's movement was severely restricted in the Rogers Cup final against Alexander Zverev.
The 36-year-old had lost the first set 6-3 to his talented German opponent but midway through the second set lost power on his serve.
He suddenly appeared out of sorts allowing Zverev to break serve in the seventh game to pull ahead 4-3 and then hold on for a surprise win that took just 68 minutes.
Federer has struggled with back problems in the past and now faces a race against time to be fully fit before the US Open begins on August 28.
Wimbledon winners through the years
Sun, July 16, 2017
Express Sport takes a look back at all those players who have won at WImbledon over the years.
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2017 – Garbine Muguruza
But Zverev was poised and aggressive off the ground from the outset rarely giving Federer time to dictate.
The 20-year-old German, who arrived in Montreal fresh off his triumph in Washington and the latest win improved his record to 5-1 in finals this year with the only defeat coming at the hands of Federer at Halle.
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