Roger Federer firmly dismissed Pat Cash's claim that taking a medical timeout before the deciding set of the Australian Open final was "legal cheating".

Federer left the court for treatment after Rafael Nadal levelled an epic showdown at Rod Laver Arena and the Swiss great returned to win 6-4 3-6 6-1 3-6 6-3 on Sunday.

Former Wimbledon champion Cash was not impressed with Federer's exit, saying on BBC Radio: "You can't just stop a marathon if you're tired. I can't stress how bad this has been supervised or looked at by the medical team here in the whole tour.

"It's wrong, wrong and wrong. It's cheating and it's being allowed. It's legal cheating, but it's still not right."

When asked about Cash's comments, 18-time major-winner Federer said he had done nothing wrong and felt the criticism was harsh.

He said: "I explained myself a couple of days ago after the Stan [Wawrinka semi-final] match. My leg has been hurting me since the [Noah] Rubin match [in the second round].

"I was happy that I was able to navigate through the pain. For some reason against Stan I had it from the start on both sides of the groin.

"After he took a medical timeout, I thought I could also take one for a change and see if actually something like a massage during the match is actually going to help me. It did a little bit potentially. I'm not sure.

"And then today after probably - well, I felt my quad midway through the second set already, and the groin started to hurt midway through the third set.

"I just told myself, 'the rules are there that you can use them'. I also think we shouldn't be using these rules or abusing the system. I think I've led the way for 20 years.

"So I think to be critical there is exaggerating. I'm the last guy to call a medical timeout. So I don't know what he's talking about."

Nadal said he had "no opinion" on Federer's medical timeout.