Watch: When Serena Williams called Roger Federer "the greatest of all time" after playing against the Swiss great

Roger Federer stunned the sporting world by announcing his retirement today, mere days after Serena Williams bid adieu to the game at the recently-concluded US Open.

Federer, who had earlier enthralled fans by announcing that he would be making a comeback at the Laver Cup, has now saddened the tennis fraternity by stating that the tournament, his own brainchild, will now be his last.

The maestro's announcement, close on the heels of Serena Williams' decision to "evolve away" from the game, is being viewed as the end of an era and brings back memories of a time when the two greats faced each across the net during the 2019 Hopman Cup.

Back then, the American legend had referred to Federer as the "greatest of all time," and was visibly enthused when asked what she thought of her opponent.

"Well, the guy is great. He is the greatest of all time, to be honest and both on the court and off the court, he has such charisma. He is a wonderful player," said Williams as she gushed much like a die-hard fan would.

Williams also opined that Federer's serve was "super underestimated" and went on to add that he had a "killer serve" when asked what stood out for her while playing the 20-time Grand Slam champion.

"I think, I am trying to narrow it down here, I don't know if the this is the right thing to say, but I think his serve is super under estimated. He has a killer serve like, literally, you can't read it and there is a reason why is he is the greatest. You can't be so great and not have such an awesome weapon like that. I watched him all the time but I never knew how amazing it was so hopefully I can get some tips later on. It was really impressive," Williams stated.

Roger Federer came out on top against Serena Williams at 2019 Hopman Cup

2019 Hopman Cup - Day 8

The two met in the 2019 Hopman Cup when Switzerland played the USA. Roger Federer beat Frances Tiafoe 6-4, 6-1 in the men's singles, while Williams got the better of Belinda Bencic 4-6, 6-4, 6-3 in the women's singles.

The Swiss pair of Bencic and Federer then got past the American duo of Serena Williams and Frances Tiafoe 4-2 4-3 (5-3) in the mixed doubles encounter which was played in Perth.

Williams made no secret of her admiration for the Swiss maestro, stating that she wanted to take pictures with Federer.

“It was super cool that we got to do it, at such a pinnacle point in both our careers. For me, it was super cool. Literally wanting to take pictures. I wanted to bring my baby out. Like way too excited. But it was really fun," she revealed.

Roger Federer returned the compliments and the two then proceeded to take a selfie, much to the delight of the Perth crowd.

“It was a bit nerve wracking to be honest, because all of a sudden you’re serving, especially the last serve, I’m like, ‘I’ve got to win this point but it’s Serena Williams!’ I was telling myself, maybe this is what I’ve always wanted, the big moments like this. I made the serve but actually totally missed the target, and thank you for missing the ball. But it was great fun and yeah, she’s a great champion. You see how focused and determined she is and I love that about her,” said the Swiss with a smile.

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