Tennis legend Andre Agassi has revealed who he thinks was the worst opponent he ever faced out of the sport's current heavyweights Roger Federer, Novak Djokovic, and Rafael Nadal.

An eight-time Grand Slam champion across his own playing career, former world No. 1 Agassi remains one of the biggest names in professional tennis after dominating the sport throughout most of the 1990's.

The American cemented his place in the Hall of Fame after also becoming the first ever male player to win all four of the sport's Grand Slam titles across three different surfaces - hard, grass, and clay.

Now, after turning to punditry since his playing days came to an end in 2006, Agassi remains a prominent voice within the modern game, and is well-loved for his honest and open take on many of the game's biggest names.

This trait certainly held true when speaking to the Economic Times this week, after Agassi was quizzed on who he felt was the worst opponent he had faced out of the three current heavy hitters within the sport - Federer, Djokovic and Nadal. 

"I had the privilege of playing all three of them. Novak was the worst of them, because he was so young, and it was only an exhibition but he still beat me," he said, as per Tennis World.

"We had Rod Laver win two Grand Slams on two surfaces, grass and clay. Nobody had come close to winning four in the same year. Federer could have done it three times with one match against one guy, but he couldn't seem to beat on clay [Rafael Nadal]."

Federer is widely regarded as being one of the greatest players ever to grace the game, but has long struggled against the dominant Nadal when it comes to playing on clay.

So dominant is Nadal in fact, that of the previous 14 French Opens to be played - the only Grand Slam to be contested on a clay surface - the Spaniard has claimed 11 of the titles on offer, losing just three of his 88 matches along the way. 

Speaking on the recent success of the sport's three largest names, however, Agassi was quick to recognise the quality of his three former opponents. 

"We are talking about historic achievements. I get it that when my generation left, Andy Roddick comes in and wins a Slam, somebody comes in and wins a Slam, but with Federer it looked like he was this guy coming in at the right time and then he ends up having to compete against two of the greatest ever, and he does it!

"So I feel like these guys just kept raising the bar of tennis."

When also pressed on the likelihood of Nadal managing to pass Federer's 20 majors within the sport, Agassi refused to rule anything out.

"If I have to make a bet, what is he at? 15? So two more for three years? Now you [Rafael Nadal] also have children, so you also have priorities in life, but if he wants to, he will!."