Actor Billy Crystal struggled through his Emmy Awards tribute to his late friend Robin Williams at last month's (Aug14) ceremony, branding the stage salute "the hardest thing" he has ever done.

The When Harry Met Sally star agreed to memorialise his Oscar-winning pal following his death days earlier on 11 August (14), and during his touching speech, Crystal remembered Williams as a comedic "genius" and "the greatest friend you could ever imagine".

However, Crystal, who reveals he and Williams used to speak "three, four times a day sometimes", admits honouring the Good Will Hunting actor in public so soon after the tragedy was a really tough task.

He says, "I think it's the hardest thing I've ever done. It was only two weeks to the day of the Emmys that everything had happened (Williams had died).

"They (Emmy bosses) called me and said, 'Would you do it?' and I said, 'Of course', but then came the task of doing it right and being sort of the spokesman for everybody, in front of 17 million people. He was my closest friend and to do it with some humour and in only a short period of time that I had to do it was difficult."

But Crystal will always have fond memories of his longtime friendship with Williams and his numerous pranks, including one he played last year (13).

He recalls, "When it was announced that I was coming back to Broadway, there was, what must have been like, 50 (phone) messages from somebody called Gary, who wanted to be my dresser. It was Robin. (He said), 'I've worked with everybody... I used to work with Carol Channing, that was a nightmare!' He'd just leave all of these phone messages and I have them all and I will always cherish them."

He adds, "There was nobody like him, ever... Robin had the amazing ability to say something that wasn't that funny, but the audience would scream because his commitment to the joke was so strong. He would just wrestle you to the ground, I've never seen anything like him and I don't think we ever will."