WATCH: 44-shot rally ended by De Minaur winner in Rotterdam

Aussie Alex de Minaur is known for having one of the quickest set of wheels in tennis, which often leads to impressive defensive displays.

That said, the 21-year-old might have outdone himself Tuesday in Rotterdam. Leading John Millman, 6-1, 4-3, 15-30, De Minaur was on his back foot throughout a 44-shot rally. Yet every time Millman looked to put away his countryman, the ball came back.

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De Minaur ended the exhausting exchange with a tremendous forehand down-the-line winner after his opponent mixed things up with a short-angled crosscourt forehand. Millman could only smile in disbelief after lightly tossing his racquet and putting his hands on his hips.

Though Millman later held to win that game, he was broken in his next trip to the line. As a result, De Minaur closed out a 6-1, 6-4 victory and set a second-round meeting with Kei Nishikori.