Roger Federer looks set to lose his world No1 ranking after losing 7-6, 4-6, 7-6 to Ivo Karlovic in the third round of the Master Series. The Swiss player has held the No1 spot for over four years, but his failure to reach the quarter-finals could see him knocked off the top spot by Rafael Nadal if the Spaniard manages to win the tournament.
Federer seemed low on confidence throughout the match against the the 6ft 10in Croatian and was finally undone by Karlovic's strong serve game. It was the world No1's second early exit in the space of two weeks after yielding his Wimbledon title to Nadal last month.
Nadal progressed to the quarter-finals thanks to a 6-4 7-6 win over Tommy Haas. Having beaten Federer at both Wimbledon and the French Open, the Spaniard is generally regarded as the world's best player. Victory in Sunday's final would make it official.