The players and announcer try to keep it together, before they realize the noises weren't coming from a phone video, but from an apartment across the lake.
Tiafoe's opponent, Mitchell Krueger, angrily blasted a tennis ball out of the court.
But during a semi-professional tennis match in Sarasota, Florida, on Tuesday, the head-turning grunting wasn't coming from the players.
Check out the video around 1:50 in.
"That is the most weird situation ..." Their match probably would've ended like any tennis match except for a women's loud, passionate moans from somewhere around the stadium.
Tiafoe, one of America's top young talents, won the match in straight sets, 6-3, 6-2.
Mike Cation who was commentating on the game said "I can still hear it".
Tiafoe, who reportedly rose almost 1,000 spots in year-end rankings according to his profile on ATP World Tour's website, won the match against Krueger, in straight sets, 6-3 and 6-2.
The broadcaster put it down to someone watching an adult video on mobile phone.
"At least somebody's having a good night", the announcer adds of the orgasmic commotion.
Not to contradict Tiafoe or anything but, judging by the sounds of it, it was pretty damn good.