Nishikori defends title

Japan's Kei Nishikori completed a successful defence of his US National Indoor Championships title with a 6-4 7-6 (7/0) victory over Ivo Karlovic in the final.

Top seed Nishikori claimed the opening set thanks to a solitary break - the first time anyone had broken the giant Croat all week - and serve was again on top in the second set.

Karlovic sent down 20 aces in total but it was to no avail as Nishikori remained resolute on his own delivery and then closed out the win without dropping a point in the tie-break after an hour-and-a-half on court.

Karlovic, 10 years older than Nishikori at 34 and more than a foot taller at 6'11", had won both prior matches against Japanese star - in last year's first round at Delray Beach and a 2012 Davis Cup meeting.

World No 16 Nishikori, 23, now has four ATP World Tour titles to his name. The others came as a teenager at Delray Beach in 2008, at Tokyo in 2012 and last year at this event in Memphis.

"It's an amazing feeling," Nishikori said. "I had never defended a title before."

American Eric Butorac and Raven Klaasen of South Africa beat Bob and Mike Bryan 6-4 6-4 to win the doubles title. It is the second time this year Butorac and Klaasen have beaten the Bryans after knocking them out of the Australian Open in January.