India, Aug. 31 -- There was something different about Jannik Sinner on Saturday night. He did not exude his usual air of invincibility. He felt more human.

"I'm not a machine," he would say later. "I also struggle sometimes."

In his first two matches at the US Open, Sinner barely put a foot wrong as he stormed past opponents without conceding more than three games in a set.

But at the Arthur Ashe Stadium in the third round, he came up against Canada's Denis Shapovalov, a southpaw who plays only in the fifth gear. Though Sinner eventually battled to a 5-7, 6-4, 6-3, 6-3 win, the Italian world No.1 showed signs of vulnerability.

"You cannot always go (through) with the scoreline easy," Sinner said at the post-match press conference. "Ev...