Kei Nishikori has described his victory over Roger Federer in round three of the Madrid Open as the biggest win of his career.
The Japanese world number 14 caused an upset in the Spanish capital on Wednesday by defeating the defending champion 6-4 1-6 6-2 to reach the quarter-finals.
It was the 23-year-old's first ever triumph over the former world number one.
"It's the biggest win for me and it's on clay which is not really my favourite surface," Nishikori is quoted as saying by Sky Sports News. "It's an amazing feeling."
Nishikori's reward for beating Federer is a quarter-final encounter with Spaniard Pablo Andujar.
