In tennis, it's rare for a low-ranked newcomer to take a major leap seemingly out of nowhere and NOT materialize into a player of significance. It takes too much innate self-belief. So I was particularly curious to watch 18-year-old Kei Nishikori play his first round match Wednesday afternoon at the SAP Open in San Jose, considering that last week he won eight matches in a row at Delray Beach (three in qualies) to capture his first ATP Tour title, knocking off ninth-ranked James Blake in the final.

It's hard to pinpoint greatness, but I came away impressed.

Nishikori, who left Japan to train at the Bollettieri Academy in Florida four years ago, had a few lapses, dropping serve several times, but he got the job done against 96^th-ranked Diego Hartfield of Argentina, winning 7-5, 6-3. The foundations upon which his game are built are solid. He hits with a breezy ease off both wings that I liked. The backhand is flatter and he can take it both directions. The forehand has more topspin (Bollettieri anyone?) and is bigger, if slightly more erratic, but a surefire weapon. He crushed several from well back in the court. His returns are hard and deep and allow him to work his way into points. He moves very well, is athletic and has the potential to be an imposing, all-court player. He wasn’t afraid to come in. He even serve-and-volleyed a few times.

What could hold him back are his size and his serve. At 5-10, Nishikori will need to develop more consistency and pop on his delivery in order to earn more free points – a must if he intends to be a top 10 player some day. Over all, his explosiveness and quickness remind me a bit of Sebastian Grosjean, or a mini-Djokovic, without the big serve.

Nishikori, who speaks passable but not great English, is typically shy and just starting to come to grips with the impact he could have in his home country, where international sporting stars generate nothing if not manic media attention. Yesterday in San Jose, numerous Japanese reporters from papers and TV stations attended his match and peppered him with questions in his post-match press conference.

“What kind of Japanese food do you like?

“Have you talked to your parents?”

"Can you win this tournament?"

His traveling coach, the former pro Glenn Weiner (who started working at IMG/Bollettieri after retiring last year), said Nishikori began to realize that he was ready to compete with the big boys when he reached the quarterfinals at Indianapolis last summer. A lower back injury hindered him for much of the fall, but that’s now fine. Earlier this year, Nishikori also smoked former French Open champ Gaston Gaudio 6-0, 6-3 in a Miami Challenger – on clay. “He didn’t tank,” insisted Weiner of Gaudio. That, too, gave him a jolt of self-belief, added Weiner.

Clearly brimming with confidence, Nishikori gets another shot at a top-10 ranked American in No. 6 Andy Roddick this evening in the last 16. Roddick wasn’t particularly impressive in his opening round three-set win over towering Chris Guccione, but if Nishikori takes out the edgy American it will be time to start talking about his prospects as the best male player ever to come out of Japan years earlier than many predicted. For now, that honor still goes to Shuzo Matsuoka, who reached a career-best No. 46 in 1992.