Serena Williams books place in Indian Wells semi-finals

Serena Williams knocked defending champion Simona Halep out of the BNP Paribas Open with a 6-4 6-3 victory to set up a semi-final with Agnieska Radwanska.

The world No 1 is yet to drop a set in four matches in Indian Wells and she looked in top form again, hammering 28 winners and seven aces.

Williams also broke the Romanian's serve four times and improved her head-to-head record to 7-1 against the fifth seed.

A right knee injury forced Williams to withdraw from the event last year, when she ended a self-imposed 14-year absence at the tournament, giving Halep a walkover in their scheduled semi-final.

Halep ultimately defeated Jelena Jankovic to capture the crown but her defeat to Williams keeps the American on course for a first Indian Wells triumph since 2001.

Third seed Radwanska stands between Williams and a spot in the final, with the American expecting a tough challenge from the Pole.

"[Radwanska] knows how to play in big stadiums and big matches, big games," Williams said.

"Obviously she does everything so well, including running, and this is a good surface for her because it's a slow surface. I think I expect there will be a lot of long rallies."

Radwanska booked her semi-final spot by beating world No 9 Petra Kvitova 6-2 7-6 (7-3), fighting back from 5-2 down in the second set.

"I am just so happy to be in the semi-finals here," Radwanska, who will rise to No 2 in the next world rankings following the win, said.

"I have nothing to lose, will have a good rest and be ready for the semis."