Serena Williams is "one of the greatest of all time", says fellow tennis legend Rafael Nadal as the 23-time grand slam winner prepares to hang up her racquet.

The 40-year-old, one of the most decorated players in the history of the sport, signalled her intent to "evolve away" from the game in an interview with Vogue Magazine earlier this month, hinting at her retirement following the U.S. Open in September.

With just shy of two-dozen grand slam singles titles, Williams trails only Margaret Court for the all-time record of 24 crowns, and could equal her in her farewell appearance.

Nadal, meanwhile, lies one behind her after victory in the Australian Open and French Open this year took him clear of Novak Djokovic and Roger Federer to 22, though the former's win at Wimbledon has seen him close the gap again.

The duo are set to feature at this week's Western and Southern Open, where Williams will face incumbent U.S. Open champion Emma Raducanu, and the Spaniard - who will mark his return from injury - has nothing but praise for his fellow giant of the game.

"She is one of the greatest sports [people] of all time," he stated. "I feel lucky to share a tour for a long period of time with her.

"Of course, from a selfish point of view, it's sad that she's leaving the tour but, on the other hand, we can't thank her enough for all the things that she did for our sport.

"I think she's an amazing inspiration for a lot of people around the world and I think she deserves to choose whatever works for her better at this stage of her life.

"So I wish her all the best. Hopefully, we can keep seeing her around the tour because I always believe that our sport, or the sport in general, is bigger and better when legends are around and she is a legend.

"Hopefully, we can enjoy her in a different way around the tour."

Nadal was forced to withdraw ahead of the Wimbledon semi-finals earlier this year with an abdominal tear, and now faces a potentially nervy run through to the U.S. Open in terms of fitness.

But the 36-year-old is cautiously optimistic, adding: "I hope to be ready. That's what I'm trying to do. Try to be a little more conservative, but I hope I can be ready to play.

"Of course, I need some more days to analyse how things are going in terms of abdominal feeling.

"But things are going well for the moment, so hopefully I can manage to be ready. I'm excited. I want to play tennis again on the tour. I'm having a good season, I'm enjoying it, so I want to enjoy this week in Cincinnati."