Roger Federer nullified the big serving of Australian Sam Groth to move into the third round of the US Open.
Groth's big claim to fame is having hit a serve of 163mph at a tournament in Korea in 2012, unofficially the fastest serve ever recorded.
The fastest Groth managed on Friday night was 147mph, and he would have known he was in trouble when a delivery of 142mph flew back past him for a clean winner.
Federer generally fares well against big servers and it was no different against Groth, although the second seed did not have things entirely his own way in a 6-4 6-4 6-4 victory.
It took the Swiss seven games to break Groth's resistance but he looked in total control when he broke again in the opening game of the second set, exploiting the Australian's relative weakness on the volley.
Groth smashed a ball towards the sky-high stands of Arthur Ashe Stadium in frustration, but a game later he was unexpectedly level.
It was no more than a workmanlike performance from Federer but he was always pushing for the opening and forged ahead again to lead 5-4 before taking the set.
Groth had never faced a top-10 player before but he was warming to his task and exploited some sloppy Federer play to break for 4-2 in the third set.
Back came Federer, though, forcing Groth to play a succession of low volleys, and when the Australian double-faulted on break point two games later the writing was on the wall.
Federer served out the victory and then said: "I thought I did pretty well from the start, I created quite a few opportunities. I'm really happy how I played on the return.
"I could maybe have done a bit better on my serve but I thought it was an exciting match. I thought Sam played well and it was tough until the end. He's got unbelievable power. My arm's still shaking a little bit."
The 33-year-old next meets Spaniard Marcel Granollers, who saw off giant Croatian Ivo Karlovic in five sets.