The defending champion won eight consecutive games en route to a comprehensive victory in California.

In the men's event, Carlos Alcaraz beat Felix Auger-Aliassime as he seeks to return to the world number one spot.

The Spanish top seed, who must win his first Indian Wells title to replace Novak Djokovic at the top of the rankings, won 6-4 6-4.

"Today, the goal was to stay there," Alcaraz said. "I knew that I was going to have my chances. Probably I played one of my best matches this season. I'm really happy and [I want to] keep going."

Alcaraz will face Italy's Jannik Sinner for a place in the final, after the Italian overcame American defending champion Taylor Fritz 6-4 4-6 6-4.

In the men's doubles, Britain's Neal Skupski and Dutch partner Wesley Koolhof beat Jamie Murray and Michael Venus 6-3 6-3 to reach the semi-finals.

They will meet Edouard Roger-Vasselin and Santiago Gonzalez in the last four after their 2-6 6-2 10-7 victory over Briton Lloyd Glasspool and partner Harri Heliovaara.

The winner of the French and US Opens last year, Swiatek will play Wimbledon champion Elena Rybakina on Friday.

Kazakhstan's Rybakina, who beat the Czech Republic's Karolina Muchova 7-6 (7-4) 2-6 6-4 in her quarter-final, knocked Swiatek out of the Australian Open in January.

Swiatek, who beat Briton Emma Raducanu in the fourth round, is looking to become just the second woman, after Martina Navratilova in 1990 and 1991, to win back-to-back titles at this tournament.

Cirstea recovered an early break and batted off a break point to level the opening set at 2-2 before Swiatek steamed through the next eight games on the way to a comfortable victory in one hour and 22 minutes.

Meanwhile, Greece's Maria Sakkari rallied from a set and a break down to beat Petra Kvitova 4-6 7-5 6-1 to secure a second consecutive Indian Wells semi-final spot.

Kvitova started well - having secured a dramatic match-point saving win over Jessica Pegula a day earlier - to take the first set and immediately break Sakkari in the second.

But Sakkari came from 40-0 down in the final game to force a deciding set, which she won in dominant fashion.

The 27-year-old will now face Australian Open champion Aryna Sabalenka, who moved into the semi-finals with a 6-4 6-0 victory over American Coco Gauff on Wednesday.