LONDON - Former champion Simona Halep was knocked out of the semifinals at the Wimbledon Championships by Elena Rybakina from Kazakhstan in straight sets on Thursday.

The former world No.1 has been showing great form since arriving at the All England Club, winning all five matches in straight sets.

But the 30-year-old Romanian struggled in her service games on Thursday as she made nine double faults during the match, losing to her big server opponent 6-3 and 6-3.

"I improved a lot in my serve the last three months. But today I feel like I went back to my normal one. Many double-faults and too soft," said Halep, who couldn't defend her title in 2020 as the tournament was cancelled due to the COVID-19 pandemic and missed last year's competition with a calf injury.

Rybakina, whose previous best result at a Grand Slam was a quarterfinal finish at last year's French Open, didn't expect she would go this far at the grass-court Grand Slam this year.

"It was tough because I had injuries, I didn't have good preparation," said the 23-year-old. "So I came here a bit more relaxed and maybe it helped me to get through all these matches. "

Rybakina is going to face Ons Jabeur in Saturday's final as the Tunisian saw off her close friend Tatjana Maria of Germany 6-2, 3-6, 6-1.

Jabeur became the first Arab player in a Grand Slam final and also the first African woman in a Grand Slam final in the Open Era.

"I am a proud Tunisian woman standing here today," said the 27-year-old world No.2. "I try to inspire as much as I can. It is not just Tunisia. I want to see more and more Arab-African players on the tour. I just love the game."

On Friday, six-time men's singles champion Novak Djokovic will fight for a final berth against British ninth seed Cameron Norrie.

Australian Nick Kyrgios received a walkover into the final as Spain's second seed Rafael Nadal withdrew from the Championships due to abdominal injury on Thursday.

22-time Grand Slam champion Nadal held back his pain in the quarterfinals on Wednesday to edge out American Taylor Fritz in five sets.

He said it's confirmed that he has a tear in the muscle in the abdomen and he has been thinking the whole day about the decision to make.

"I think it doesn't make sense to go on," he said on Thursday evening. "Even if I tried a lot of times during my career to keep going under very tough circumstances, in that one I think it's obvious that if I keep going, the injury will get worse and worse. That's the thing that I can say now. I feel very sad to say that, it's a very tough one."