In this picture, Roger Federer of Switzerland congratulates Novak Djokovic of Serbia after their match during the men's final of the Western & Southern Open at Lindner Family Tennis Center in Mason, Ohio, Aug. 19, 2018.

Roger Federer heaped praise on Novak Djokovic after the latter became the first player in tennis history to achieve a Career Golden Masters following his win in the Cincinnati Masters final Sunday.

Djokovic was facing Federer for the first time since the Australian Open in Jan. 2016, and defeated the Swiss legend 6-4, 6-4 to win the only Masters 1000 title to have eluded him in his trophy-laden career.

It only adds to Djokovic's unique accolades which include being the only player to have a winning record over Federer and Rafael Nadal, the first player since Rod Laver in 1969 to hold all four Grand Slams at the same time, and the most points accrued in an ATP season — all of which could see him seriously considered in the tennis GOAT debate.

And Federer believes winning every single Masters 1000 title may be the one achievement which defines Djokovic.

"All these records that a player creates, at the end you're going to all judge it all together, bundle it up and say, ‘Okay, what was the coolest thing you ever did?'" Federer said, according to the Express. "This might be it for Novak besides winning all the Slams and all the other things he's done already. He's a great champion and this is what this should be about. It's about him making history."

"We can go into whatever points you want, but I think that's what the headline should be about. This is an amazing accomplishment, and I hope he's extremely proud and extremely happy about this moment," he added.

Djokovic meanwhile, was undoubtedly pleased with his achievement, especially as he was a previous runner-up on five occasions in Cincinnati, with three of those losses coming at the hands of Federer.

While making history was in the back of his mind, Djokovic was ultimately pleased with his performance that led to one of the "most special moments" in his career.

"Definitely one of the most special moments in my career," Djokovic told the assembled media. "Achievements, making history in the sport that I truly love is a great privilege and honour and something that I'll be very proud of for the rest of my life. I was saying previously that during this week this trophy has been a motivation. A big motivation for me. But at the same time I tried not to think about the pressure of really making history too much, because I have had already some failed attempts."

"Coming into today's match, it wasn't easy psychologically because I knew I lost to him [Federer] every time I played him on this court. But at the same time, I liked my chances because I felt better and better as the tournament was progressing. It was by far the best performance of the week," he said.

The Serbian also admitted he initially thought the last time he faced Federer was a year ago and was surprised to learn it was even longer. It did however, allow him to have a clean slate mentally, as he went on to praise Federer and Nadal for helping him become a better player.

"For me it was fresh because it's the first time that I won this trophy and against him here. It's a pleasure to share the court with him, with the all-time great and I truly mean that," Djokovic explained. "With him, with Nadal, these guys have been such an integral, important part of my life and my career and my evolution as a tennis player. They make me play my best tennis. They make me improve. They made me think about what I need to do in order to try to be the best player in the world."