HE is the man dubbed "Special Kei". The star graduate from Project 45.

Yet to most tennis fans, Japan's Kei Nishikori remains an enigma who shot to prominence with a shock Australian Open quarter-final last year and has the prized scalp of world No.1 Novak Djokovic on his record.

Now ranked 19th in the world, Nishikori is looming as a major player in the Brisbane International following a clinical 6-3, 6-3 second round defeat of former top 10 Spaniard Tommy Robredo yesterday.

"I'm struggling a little bit on my return but it's coming," Nishikori said.

"I hope I can be top 10 at the end of this year. That is my goal. It's going to be tough because I had so many injuries these past couple of years but if I can be healthy all year I think it is possible to get into quarter-finals and semi-finals now at Grand Slams."

The 23-year-old is considered one of the richest men on the ATP tour, not because of his career earnings which sit at a tad over $1 million, but because he is Japan's biggest current export in tennis.

He was sent to Florida when he was 14, part of the Masaaki Morita Tennis Fund Group where select Japanese players were funded by Sony's chief executive to find a new champion.

It was known as "Project 45", as that was the nation's previous highest men's ranking.

Ironically though Sony was one of Nishikori's major sponsors that let their contract expire in 2011, two months before his Grand Slam breakthough that captivated Japan.

His third round win over Jo-Wilfried Tsonga in Melbourne last year was watched by over 55 million in Japan.

Nishikori's new clothing sponsor had immediate calls about starting a tennis line of apparel such was his popularity while Wilson now sell racquets carrying his name in Asia.

Mobbed and hounded by media in his hometown, Nishikori enjoys the anonymity of the US, where he plays out of the Nick Bollettieri academy.

In 2011, he was coached by Brad Gilbert, former mentor to Andre Agassi and Murray, where his rapid improvement really hit top gear.

According to those tennis experts, Nishikori is bound for a single digit ranking very soon.

"If Kei's serve continues to improve, and if he continues to play an attacking game, he could end up becoming a top 10 player," Bollettieri said last year.

"He's gaining so much self-confidence now, and that's great. When he first came to my academy in Florida, as a young teenager, he could not speak a word of English, and he was homesick - it wasn't easy for him.

"I think the fact that his English has improved so much has helped him. It has enabled him to communicate with the crowd and with his coach. Now he is the highest ranked Japanese in their history. He's a great player, he has great movement, and he's a shot-maker."