Sorana Cirstea earned the biggest win of her career, defeating World No.2 Aryna Sabalenka to reach the Miami Open semi-finals. Unseeded Romanian Cirstea stunned the Australia Open champion Sabalenka in straight sets 6-4, 6-4 in Wednesday’s quarter-finals. For the first time in 10 years, Cirstea will play in the semifinals of a WTA 1000 event. In her first meeting with Sabalenka, Cirstea produced a stunning performance to beat the Belarusian and advanced to the penultimate round of a major tournament for the first time since finishing runner-up to Serena Williams in Toronto in 2013.

Cirstea, who has yet to drop a set in five victories, showcased a play with high-level energy and dominated right from the start. The 32-year-old Romanian took advantage of some untimely double faults to become only the third person to beat Sabalenka this year. Cristea has also beaten No.5 seed Caroline Garcia this week.

Cristea tied Sabalenka with seven aces and hit just two double faults to her opponent’s six. Three of them came at the worst possible time for Sabalenka, on break point. Cirstea broke initially to open the match but the top-seeded Belarusian dropped just three points across her next three service games before breaking Cristea to draw level at 4-4. But Cirstea held firm against Sabalenka’s power and broke right back before sealing the first set in emphatic fashion with an ace.

Cristea broke again in the first game of the second set when Sabalenka double-faulted at 30-40 and then held to love for a 2-0 lead. But the Belarusian quickly turned up the heat and found her way before letting it slip. Sabalenka, a runner-up at Indian Wells, threw away a break point chance while she was leading 3-2.

She then double-faulted while facing a break point in the next game. Cirstea capitalized on all the errors and opportunities to go ahead 4-3. When serving for the match, Cirstea fell behind 0-30 and then held steady to save two break points before finally sealing the win.

I think I am a bit speechless. I came out knowing that it is going to be a really tough match. Aryna hits so hard, so I knew I had to hold my ground, and I am very, very happy with my performance today, Cristea said after registering a memorable win.

Cirstea will face either Czech 15th seed Petra Kvitova or Russian Ekaterina Alexandrova in the semis on March 31.