For most of her US Open third-round match against Elise Mertens, Madison Keys was the aggressor. The American No.14 seed aimed to get on the front foot with her power, while Mertens sought to counter it with pinpoint lobs and the variety she's honed on the doubles court.

US Open: Scores | Draw Order of play

But at the start of the second set, Keys showed that she can be as speedy as anyone out there -- and combined it with her fast arm for a spectacular hot shot. With Mertens at net, Keys hared across the court to slam home a forehand pass down the line and into the corner.

However, it was No.33 seed Mertens who ultimately won through 6-7(5), 7-5, 6-4 in 2 hours and 54 minutes to face No.2 seed Aryna Sabalenka in the fourth round. Having lost her first three encounters with Keys in straight sets, including in the 2017 US Open first round, Mertens has now won their last two in three sets.