Rafael Nadal has set the record straight on his decision to leave his wife in hospital to compete at the US Open last year, paying tribute to the 'brave' mother of his child.

Nadal and his wife, Xisca Perello, welcomed a baby boy named Rafael Jr in October last year, but there were complications with the pregnancy and she was required to spend time in hospital in September.

However, Nadal opted to head to New York for the US Open, leaving the doctors to monitor his wife in Mallorca while he looked to add to his haul of grand slams.

That decision resulted in heavy backlash from fans, but the 36-year-old has clarified what really happened last year.

'Luckily, I have a woman who is brave,' he said in Sydney. 'And she has always helped me in everything I could and more, and she has always encouraged me to continue.

'So, in that sense, she made it easy for me. In fact, it was she who encouraged me to go to the United States.'

Shortly after the US Open, Nadal headed to London to feature in Roger Federer's emotional tennis farewell. Given that his wife was heavily pregnant back in Spain, the Swiss superstar greatly appreciated his friend's kind gesture.   

'I called him after the US Open - I waited for him to finish that tournament - just to let him know about my retirement,' Federer said.

'Rafa told me, "I will try everything I possibly can to be there with you." And that felt obviously incredible for me. And it showed again how much we mean to one another and how much respect we have.

'And I just thought it would be just a beautiful, amazing story for us, for sports, for tennis, and maybe beyond that as well, where we can co-exist in a tough rivalry and come out on top and show that, hey, again it's just tennis. 

'So, an incredible effort by Rafa, and I'll obviously never forget what he did for me in London.'