Melbourne – Japan's Kei Nishikori won high praise from Rafael Nadal Monday as the world number one tipped him to break into the top 10 following their hard-fought encounter at the Australian Open.

The Japanese star, advised by Michael Chang, kept the 13-time Grand Slam champion on court for three hours 17 minutes before going down 7-6 (7/3), 7-5, 7-6 (7/3) in the fourth round.

Asia's most accomplished men's star said he was proud of his efforts, but also disappointed to lose his sixth straight match to the mighty Spaniard and fail to take a set.

“First of all I'm really disappointed because I had some chances to at least get one set, and I couldn't,” he said.

“I mean, both tiebreaks he was playing much better. He raised his level and he was playing good.

“But a couple points was amazing points. I thought I was playing good. Some important points I couldn't get and the games can change completely.

“So, you know, I think that was the best game I have against Rafa.”

Nadal said Nishikori had come a long way in a short time and had a bright future.

“It's always it's tough against him on every surface,” said the Spaniard.

“He's a very complete player. He's very quick, he's able to do the most difficult thing in tennis, that's taking the ball early and changing the direction. He's able to do it easy.

“Kei is a potential top 10 player.”

Nadal added: “It was difficult for me to take positions inside the court and I was close to losing every set, so I congratulate Kei and I feel he will have a great season.”

Nishikori, who is currently ranked 17, has hired former French Open champion Chang to help him crack the top 10, working alongside his current full-time coach Dante Bottini. – Sapa-AFP