US Open villain Stefanos Tsistipas was up to his usual antics in the third round against Spanish teen sensation Carlos Alcaraz, which sparked a divisive response from the American crowd.
The World No.3 made headlines following his win over Andy Murray when his extended bathroom breaks infuriated the Scot.
In Thursday's second round match against Adrian Mannarino the issue reared its ugly head again, which sparked boos from the crowd.
However, the division from the crowd was taken to another level in his latest match with the Spanish teen as the pair pushed each other to five-sets.
Tsistipas not only took his regular bathroom breaks, but was also warned for a coaching violation during the third set.
This sparked a fierce reaction from the crowd as they heckled the World No.3.
The crowd was so anti-Tsitsipas that some spectators from other courts took to social media and claimed they could hear the crowd.
However, this sparked controversy.
The pair put on arguably the match of the tournament, but the crowd were cheering many of Tsistipas' mistakes.
Viewers became divided over the treatment of Tsitsipas, considering he hadn't broken any rules under the Grand Slam laws.
Many felt the booing was excessive and the crowd should have been more partisan considering the high-quality level of tennis on show.
Carlos Alcaraz downs Stefanos Tsitsipas in US Open thriller
Despite the controversy, a star was officially born after Alcaraz prevailed in a raucous atmosphere to knock out Tsitsipas 6-3, 4-6, 7-6, 0-6, 7-6.
The 18-year-old Spaniard, who is a fan of Rafael Nadal, clawed his way back in the third set when the match was looking to get away from him.
After Tsitsipas looked like running away with the match in the fourth, Alcaraz bounced back and pushed it to a fifth-set tiebreak.
With the crowd roaring on the Spaniard, the 18-year-old took the tiebreak with some sweeping shots to cause the shock of the men's draw so far.
"I think without this crowd, I don't have the possibility of winning this match," an emotional Alcaraz said.
"Thank you. Thanks for pushing me up in the fifth set. An incredible feeling."