Sabalenka ends Andreeva adventure to reach Madrid quarters
Russian youngster Andreeva, a wildcard, became only the third 15-year-old to win a WTA 1000 main draw match when she beat 2021 US Open finalist Leylah Fernandez last week.
She went on to beat two top 20 players in Beatriz Haddad Maia and, on her 16th birthday, Magda Linette, but overcoming 2021 Madrid winner Sabalenka was a bridge too far.
"Of course I'm happy with the win, I wish I would have played at Madrid when I was 16," said Sabalenka.
"I think my first few games I was trying to adjust for her rhythm and her game, and then I kept trying to play my game, be aggressive and fight for every point."
Sabalenka broke Andreeva in the first game but the world number 194 immediately responded to get back on serve.
The Belarusian converted her second break point in the fifth game for a 3-2 lead and again broke to clinch the first set 6-3.
Sabalenka, second seed in Madrid, won 67 percent of points in a convincing second set to reach the last eight.
The Australian Open champion will face Egyptian Mayar Sherif in the next round after she beat Elise Mertens 6-4, 0-6, 6-4 earlier Monday.