Pat Cash: "Nadal brought something to the tennis world that had never been seen before".

In the wake of Rafael Nadal's retirement, many in the tennis world are paying tribute to the Spaniard.

Many thoughts emerge on Nadal's legacy. Pat Cash was full of praise: "Nadal brought something to the tennis world that had never been seen before.

I've always said he was like a turbocharged Guillermo Vilas. Vilas came onto the circuit playing with more lift than anyone else. He was in better shape than any player you'd seen before.

He was dedicated to running, running non-stop. He trained like crazy. Rafa is an improved, turbocharged version of that.

But we've never seen anyone play like Rafael Nadal. His follow-through. It was unusual, with an exaggerated amount of lift.

I've always said that if I had to choose one person to play my life in a match, it would be Nadal. If an alien came down from space and told you he could beat anyone, you'd show him Rafa.

Try to stop his slice serve, his lift. He plays like nobody else. Every season was interesting because you knew something had changed, something had improved, constantly.

He changed his serve and improved it. He used different tactics: that's what the best players do."