STOCKHOLM : Japan's teenage tennis sensation Kei Nishikori dismissed his own illness worries to advance into the semi-finals of the Stockholm Open on Friday as ailing opponent Mario Ancic withdrew with fever from their quarter-final match.

Third seed Jarkko Nieminen continued his quest to try to go one better after losing two finals, with the Finn stamping his authority on Spaniard Oscar Hernandez 6-1, 6-4.

Nishikori said that he had considered retiring himself before the match after carrying a cold, sore throat and knee pain all week.

"But I didn't, I just wanted to play the match," he said. "I'm sick too. But I'm in the semi-finals, that's big."

Ancic, who missed six months of play in 2007 with a serious case of glandular fever and was out for much the summer with a relapse, was unable to take to the court.

The second-seeded Croatian was struck down by fever and bronchitis to hand the 18-year-old Nishikori a first semi-final since Delray Beach in Florida last February.

Nishikori, ranked 77th is fast-tracking up the ATP rankings and is carrying the hopes of his country as the first serious contender from his nation since Top 50 Shuzo Matsuoka a decade and a half ago.

Nishikori, who has lived for the past four years at the Nick Bollettieri academy in Florida, won his first career title in Delray as he beat number 12 James Blake in the final.

He will await an opponent as he continues his successful Stockholm debut from Swedish fourth seed Robin Soderling and German number five Rainer Schuettler.

Top seed David Nalbandian was aiming to polish his indoor game in preparation for the Davis Cup final under a roof next month against Spain in Cordoba, his hometown.

Nieminen, losing Stockholm finalist in 2001 and 2006, broke Hernandez five times in just under 90 minutes on his way to victory.

The 27-year-old playing the event at the Kungligahallne for the ninth straight time, improved to 14-8 at what he considers his "home" event.

He currently stands 33rd, down from a career-best ranking of 13th in summer, 2006.

- AFP /ls