World number one Roger Federer suffered a shock 3-6 6-3 7-6 defeat by Australian Thanasi Kokkinakis in the Miami Open second round early this morning South African time.

It was the second loss in six days for the Swiss champion, who was beaten by Juan Martin del Potro in the Indian Wells final.

Federer is set to lose his top ranking to Rafael Nadal, even though the Spaniard is not playing in Miami.

Kokkinakis, ranked 175th in the world, used a vicious top-spin forehand to wear down the defending champion and claim an upset victory in front of a stunned near-capacity crowd.

The 21-year-old Kokkinakis, only got into the Miami qualifiers on a wildcard.

But he displayed the talent that has long had him earmarked as one to watch, improving the longer the match progressed.

There were few danger signs for the Swiss maestro and 20-times grand slam champion, Federer.

Kokkinakis pounced and the whole tone of the match shifted.

He went toe-to-toe with 36-year-old Federer and dominated the tiebreak, winning on a second serve that Federer sent into the net.

Australian tennis player Thanasi Kokkinakis says:”It was an unreal win for me, I mean I’ve trained with him a lot of times, you know I’ve looked up to him, obviously he’s such a good role model for the sport, playing unbelievable tennis this year, he’s invited me to Dubai to train a few times and then I took what I’ve learned from him and then sort of, kind of knew how he played a little bit and just played my game and executed.”

Grand slam champion Roger Federer says:”Look it’s disappointing, don’t know why I didn’t, could never get to any level that I was happy with today but sometimes you have these matches and sometimes you find a way through and just I couldn’t get it done today.”

In other action, fourth seeded German, Alex Zverev battled past unseeded Russian Daniil Medvedev 6-4 1-6 7-6.

While tenth seeded Czech, Tomas Berdych, defeated Japan’s Yoshihito Nishioka 6-1 6-4.