Kei Nishikori beat American Ryan Harrison 6-4, 6-4 in the second round of the BNP Paribas Open on Saturday, while defending women's champion Flavia Pennetta easily advanced.

Playing in 91-degree heat, Nishikori dispatched Harrison in 1 1/2 hours despite struggling with his first serve. The fifth-ranked Japanese player reached the third round at Indian Wells for the first time in eight tries.

Nishikori arrived in the desert on a roll, having reached the quarterfinals or better at each of his four previous tournaments this year. He won the title in Memphis.

Harrison fell to 1-24 against top-10 players in his career.

Pennetta beat American Madison Brengle 6-4, 6-2 as the Italian opened defense of the biggest title of her career.

Two-time winner Maria Sharapova was to play later, while defending men's champion Novak Djokovic competes in an evening match.