Andrey Rublev has heaped praise on Roger Federer and Rafael Nadal for changing the game in the last decade and admits that he had no doubts about their ability to return to winning ways after struggling with form and fitness issues in recent years.

The duo's on-court rivalry that began in Miami in 2004 has transcended the game of tennis and has taken the sport to the next level in terms of quality and popularity.

Nadal and Federer have won a combined 35 Grand Slam titles and are currently ranked number one and two in the world, respectively. The duo did struggle to compete at the highest level in recent years owing to form and fitness, but showed that they can still challenge for the important titles in 2017.

The Swiss ace won two major titles in 2017, but his last triumph in a Grand Slam prior to that was in 2012. Similarly, the Spaniard also captured two Grand Slam titles last year with his previous major title coming at the French Open in 2014. Apart from that, the duo won a combined nine titles on their way to the top of the world ranking.

Nadal and Federer struggled with injuries in 2016 when questions were raised about their future in the game, but they silenced their doubters with a successful 2017 campaign. Rublev admits that he never doubted the duo's capability to return to winning ways while labelling the 36-year-old Swiss star the 'best ever'.

However the 20-year-old Russian, who is currently ranked number 32 in the world, believes that there will be players better than Nadal and Federer in the future similar to how the aforementioned duo took over from previous greats Pete Sampras, Andre Agassi and Boris Becker among others.

"I always thought that Rafa would win again after all the problems he had," Rublev said, as quoted by Tennis World USA.

"And Federer is the best ever. They have changed tennis and continue to be the best. I am sure that in the future there will be someone better than them. In tennis, it has always been like this. It may take a lot of time but there will be replacements," the Russian added.

Andrey Rublev
Andrey Rublev believes there will be replacements for Federer and Nadal in the future Getty