Daniil Medvedev went on to defeat Feliciano Lopez in four sets.
CNN  — 

Daniil Medvedev has become this year’s US Open villain.

The Russian defeated Spaniard Feliciano Lopez 7-6(1), 4-6, 7-6(7), 6-4 – his second four-set win in consecutive days – but it was his unruly behavior on the court that had fans lustily booing the 23-year-old at Louis Armstrong Stadium in Friday’s night session.

In tennis, it’s beyond difficult to transition from teen prospect to grand slam winner. Roger Federer, Serena Williams, Rafael Nadal and Maria Sharapova are the high-profile exceptions rather than the rule.

Later, after a confrontation with Dumusois, TV cameras picked up Medvedev putting a hand to his head giving the middle finger – outside of the view of Dumusois. Boos rained down from the crowd, and Lopez quickly became the fan favorite.

After he won, surrounded by boos, Medvedev raised up his arms, motioning to the crowd to keep going.

“Thank you all, guys, because your energy tonight gave me the win,” Medvedev said in an interview on court. “Because if you were not here, guys, I probably would lose the match. Because I was so tired, I was cramping yesterday. It was so tough on me. So I want all of you to know when you sleep tonight, I won because of you.”

The boos continued.

“The energy you’re giving me right now, guys, I think it will be enough for my five next matches. I mean, the more you do this, the more I will win for you guys.”

Controversy nothing new for Russian

Controversy is nothing new when it comes to Medvedev. In 2017 at Wimbledon, he was fined $14,500 for several infractions, including tossing coins in the direction of chair umpire Mariana Alves after a five-set loss.

He was disqualified from a Challenger event a year earlier in Georgia for making a racist remark. Aggrieved that a call went against him when playing Donald Young, he said to the chair umpire Sandy French – Young and French are both black – “I know that you are friends. I am sure about it.”

He later apologized.

The Russian, seeded fifth, has dominated on the hard courts this summer, including winning his first Masters 1000 title at the Western & Southern Open in the Cincinnati suburb of Mason, Ohio, earlier this month. His next opponent will be 118th-ranked qualifier Dominik Koepfer.