INDIAN WELLS (UNITED STATES) - Serena Williams dethroned defending champion Simona Halep in straight sets to set up an Indian Wells semi-final showdown between the world No. 1 and 2.
Serena Williams of the US celebrates scoring a point against Simona Halep of Romania during their BNP Paribas Open women's singles quarter-final match, at the Indian Wells Tennis Garden in California, on March 16, 2016
Williams reached just her second semi in 15 years by beating Halep 6-4, 6-3 on Wednesday.
"She's a dangerous player," Williams said of Halep. "She knows what it takes to beat the best player so I knew I had to play as best as I could."
Williams advances to face Agnieszka Radwanska, who has never beaten Williams in nine career matches.
Fifth seeded Halep was the one who helped spoil Williams' much-anticipated return to the WTA and ATP Tour tournament last year, winning their semi-final in a walkover after Williams pulled out right before the match with a knee injury. Halep went on to beat Jelena Jankovic in the final.
It was all Williams on Wednesday as the 21-time Grand Slam winner played as if she had something to prove, blasting six aces and winning 80 percent of her first-serve points.
"Feels good to get that win," Williams said. "I had to buckle down."
Last year's semi-final withdrawal by Williams cut short her first Indian Wells campaign since 2001, when spectators booed her during the final and jeered her sister, Venus, and father Richard Williams after the pair arrived to watch the match. Richard Williams alleges he heard racial comments.
That scene sparked a lengthy boycott by both Williams sisters as Venus made her long-awaited return this year, but lost in her opening match to Japanese qualifier Kurumi Nara.
Radwanska defeated Petra Kvitova 6-2, 7-6 (7/3) in their quarter-final, but the victory had an added bonus as she vaulted past Angelique Kerber into the world number two spot.
It was just the fourth time Radwanska has beaten Kvitova in 10 career meetings.
Kvitova dug deep in during the second set, breaking Radwanska twice for a 4-2 lead. Radwanska came racing back, drawing from her arsenal of shots to force a tiebreaker.
Radwanska got off to 4-0 lead in the tiebreaker then held on to clinch it when Kvitova dumped a backhand into the net.
"I was pretty calm," Radwanska said of her second-set comeback. "Obviously that's just one break, so you just keep going. And I was a little big lucky, in the end."