Sabalenka ended Keys' 16-match winning streak and got some revenge for her loss to the American in the Australian Open final. Keys beat Sabalenka in three sets in January at Melbourne Park, denying Sabalenka a third consecutive title.
"I didn't expect this match to be that fast," Sabalenka said. "I'm super happy with the way I played today -- much-needed revenge."
Sabalenka, who reached the Indian Wells final in 2023, said she was looking forward to playing the teenage Andreeva.
"It feels like old mama playing against the kid," Sabalenka, 26, said. "I'm like what, nine years older than her? She is two years younger than my sister and I look at my sister as a kid. It's crazy."
Revenge is also on the mind of Andreeva, who lost to the world No. 1 in straight sets in the fourth round of the Australian Open.
"I'm going to try to take revenge because I still have nothing to lose," Andreeva said. "I feel like the match is going to be entertaining. There are going to be a lot of winners, a lot of great points."