'The guy is a genius,' Serena Williams hails Roger Federer

Roger Federer or Rafael Nadal or Noval Djokovic – who is the greatest of all time? There have been several debates over the years to determine the answer but Serena Williams has made her choice.

In an interview with ATP's official website on Monday, Williams heaped praise on Federer, calling him the "synopsis of greatness and class."

Last year, Nadal equalled Federer's tally of 20 Grand Slam titles, while the World No. 1 Djokovic currently holds 18 major titles.

On Monday, Williams beat Lisa Pigato, the 17-year-old qualifier, 6-3, 6-2 in the opening round of the Emilia-Romagna Open, Parma to mark her first win in over three months.

After the win, Williams spoke about Federer, who is due to play his second tournament of the year since returning to the tour in March after being out of action for more than a year due to two knee operations. Federer will be in action at the Geneva Open on Tuesday. He will take on Spain's Pablo Andújar.

"I think two words sum it up: Roger Federer. He's just a synopsis of greatness and class and amazing and really changed the game. You see players playing like him, moving like him, doing his techniques. The guy is [a] genius," Williams told ATP's official website of Federer's legacy.

The 23-time Grand Slam winner also went on to admit that she is a "superfan" of Federer.

"I just feel like he is really the greatest player. Just look at him. You can't not like the guy, that's how I feel. His game is so fantastic. If I could only play like him!" added Williams.

Last week, Williams faced a first-round exit at the Italian Open. She was then handed a wild-card invitation for the Parma tournament.

"I'm just starting to feel more comfortable. I've always felt super comfortable on the clay and this year has been a little more difficult than normal. I think it was because of the long hiatus I've had (from) the clay," said Williams, who dominated her young opponent in the first round on Monday.

Williams is set to take on Czech Republic's Kateřina Siniaková in Round of 16 in Parma on Tuesday.