Japanese hope Kei Nishikori put friendship to one side on Wednesday as he beat long-time practice partner Austin Krajicek to reach the Australian Open third round.
The seventh seed had to fight in the second set before winning 6-3, 7-6 (7/5), 6-3 in one hour, 53 minutes on Margaret Court Arena with the roof closed after morning rain.

Nishikori, the 2014 US Open runner-up, who has yet to pass the quarter-final stage at Melbourne Park, will next play Spain's 26th seed Guillermo Garcia-Lopez.

Nishikori and Krajicek grew up training together at the Bollettieri Tennis Academy in Florida, and they were playing competitively for the second time after the Japanese star won in three sets in Memphis last year.

"I tried to forget in the match. But it's never easy to play with good friends and especially I knew him when we were like 15, 16," Nishikori said.

"So it's not easy, but on the court I try to concentrate on whoever is over the net.

"I should have closed out the second set when it was 5-4 but he started playing better and it was a tight tie-break. Once I got the tie-break I was better."

Nishikori breezed through the opening set in 25 minutes following a service break in the fourth game.

But Krajicek raised his level while Nishikori had a stutter in an hour-long second-set struggle.

The Japanese player was broken serving for the second set when he double-faulted and he was far from convincing in the tiebreaker, before finally sealing it when the American's forehand went wide.

Nishikori stepped it up in the final set with an early break to ease to victory.

"I think mostly I was controlling the points. I was trying to play quick, because he can be really dangerous, especially with the roof closed," Nishikori said.

"He has a great serve, and the last time we played he was much more aggressive. He came to the net little more.

"But what I did well today, was to hit deep a lot of times to stop him coming in. I served really well today."

Source: AFP