Serena Williams reaches Indian Wells semi-finals

Serena Williams will face Romanian Simona Halep in the semi-finals at Indian Wells

Serena Williams reached the semi-finals of the BNP Paribas Open at Indian Wells, beating Timea Bacsinszky.

Top seed Williams saw off the challenge from the Swiss 7-5 6-3 to extend her winning streak to 15 matches.

The American will play Romania's Simona Halep, who beat Carla Suarez Navarro 5-7 6-1 6-1, in the last four.

The other semi-final is between Jelena Jankovic and Sabine Lisicki, who saved three match points before knocking out defending champion Flavia Pennetta.

German Lisicki eventually triumphed 6-4 6-7 (3-7) 7-6 (7-4), while Jankovic was beating Lesia Tsurenko 6-1 4-1 before the unseeded Ukrainian retired due to an ankle injury.

The Romanian is the most recent player to beat Williams last autumn at the WTA Finals in Singapore.

The American is playing at Indian Wells for the first time since ending her 14-year boycott of the event.

"I'm just happy I was able to get through and still be alive in this tournament when I haven't clearly been the Serena that we all know," she said.

World number 26 Bacsinszky, 25, had her 15-match winning streak ended, but still leads this year's WTA Tour with an impressive 21-3 record.

She lead through a break in the opening set before world number one Williams responded with two breaks of her own to win 7-5.

The second set featured four straight breaks of serve before Williams won four of the final five games.

"The only thing is I know can I play a lot better. I really take a lot of solace in that," Williams said.

"Even if I don't win this event, I know I can play a tremendous amount better than what I have been playing."