Nishikori upsets top-seeded Cilic to reach semifinals

Marin Cilic, of Croatia, serves to Kei Nishikori, of Japan, during a quarterfinal round tennis match at the U.S. National Indoor Championships on Friday, Feb. 22, 2013, in Memphis, Tenn. (AP Photo/Mark Humphrey) (The Associated Press)

Kei Nishikori, of Japan, returns a shot to Marin Cilic, of Croatia, during a quarterfinal round tennis match at the U.S. National Indoor Championships on Friday, Feb. 22, 2013, in Memphis, Tenn. Nishikori won 6-4, 6-2. (AP Photo/Mark Humphrey) (The Associated Press)

Top-seed Marin Cilic lost in straight sets to Kei Nishikori of Japan in the quarterfinals Friday of the U.S. National Indoor Tennis Championships.

Nishikori's 6-2, 6-2 victory denied Cilic an opportunity to win back-to-back ATP World Tour titles. Cilic claimed his ninth career title two weeks ago in Zagreb, Croatia, and had won nine of 11 matches this year.

Cilic's loss left the tournament without any of its top four seeds in the semifinals. Second-seed Milos Raonic, third-seed John Isner and fourth-seed Sam Querrey were eliminated by the second round.

Nishikori, the fifth seed, reached his second semifinal of the year. He opened the year reaching the same round in Brisbane.