World No. 1 Simona Halep punched her ticket to the Indian Wells semi-finals with a 6-4 6-7 (5/7) 6-3 win over Croatia’s Petra Martic.

The 26-year-old Halep improved to 18-1 on the season and is looking to win her second WTA Tour title of 2018.

Halep, of Romania, needed two hours and 23 minutes on Wednesday to put Martic away under taxing conditions as strong winds swirled around the main stadium court.

“It was difficult conditions to play in today because of the wind,” she said. “It was tough to play, because the ball was really moving.

“But I just tried everything. I tried also to push a little bit the ball and then to hit it. I tried to mix it up. Was not easy at all. For both of us it was difficult.”

Halep moves on to the semi-finals where she will face Japan’s Naomi Osaka who beat fifth-seeded Karolina Pliskova 6-2 6-3.

Halep is guaranteed to hold onto her No. 1 ranking at the end of this event after World No.2 Caroline Wozniacki was eliminated on Tuesday.

Halep blasted two aces and broke Martic’s serve four times.

“I just fought and that’s maybe why I won because I refuse to lose,” Halep said.

Halep won the final five games of the third set after being broken once and falling behind 3-1 early.

The turning point in the third set came for Halep after she won a challenge in the eighth game with Martic holding serve. On the very next point Martic hit a forehand wide as Halep took the game and a 5-3 set lead.

Halep then served for the match, winning five of the final six points after the challenge.

Halep said her early struggles in the final set were from nerves and frustration with the playing conditions.

“I calmed myself down a little bit more, and I just was more focused on what I have to do, and not thinking that much about the wind and what is going on on court.

“I just fought till the end, and I think that’s why I could win.”

Halep is seeking her second Indian Wells title after beating Jelena Jankovic in 2015.

In the evening session, World No.44 Osaka broke Pliskova’s serve six times in her 78-minute upset on the main stadium court.

“I returned the ball well,” said Osaka. “She is one of the best servers on tour and I was able to break her quite a few times so I am really happy about that.”

Pliskova, who reached the quarter-finals at the Australian Open in January, smashed five aces but made six double faults.

Pliskova was trying to reach the semi-finals in this event for the third consecutive year.

“Everything was a little bit off from my side,” Pliskova said. “She was playing very well. Hitting her spots, forehands, even the backhands.

“I just battling all the way, even in serving and returning. I was definitely not feeling the best.”