Roger Federer's latest reign atop the world rankings will end after the Swiss great's shock loss to Australian qualifier Thanasi Kokkinakis in the second round of the Miami Masters on Saturday.

Kokkinakis, ranked 175th in the world, needed a wild card just to get into qualifying. But he showed nerves of steel in a 3-6, 6-3, 7-6 (7/4) triumph over 20-time Grand Slam champion Federer.

Federer, who regained the number one spot in February after winning the title in Rotterdam, needed to reach the quarter-finals to remain at the summit. 

Instead he'll be replaced by Rafael Nadal when the rankings are released at the end of the tournament.