Monfils, hampered by an ankle injury, prevailed 6-4 3-6 7-6(2) in a quarter-final that took two days to complete because of rain.
"Honestly I don't know," the Frenchman said when asked about his match with Nadal scheduled for two hours later. "I don't think my body is ready yet."
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"I think I showed today I was a fighter. Now I hope it is not that bad," he told ATP Tennis Radio.
But he said he was proud of the way he played on against Bautista Agut.

MONTREAL, QC - AUGUST 10: Gael Monfils of France addresses the spectators after pulling out of his match against Rafael Nadal of Spain due to injury during day 9 of the Rogers Cup at IGA Stadium on August 10, 2019 in Montreal, Quebec, Canada. (Photo by Mi

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The ankle started bothering Monfils in the second set, but after a visit by a physio he elected to continue.
Bautista Agut won the set comfortably and the third went to a tiebreak which Monfils led 5-0 before sealing victory with a huge forehand winner after more than two hours.
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