It was a glorious performance from the fearless teenager ranked 87th in the world, as one of the pre-tournament favourites was taken out with a combination of devastating baseline hitting and serves in 65 minutes.
Sabalenka's rise up the WTA rankings to 11th in the world has not encountered many roadblocks along the way, but she appeared lost in the first set in the face of a very good performance from the 2017 Junior US Open champion.
'You are kidding me!' - Unreal winner from teen sensation Anisimova
Anisimova was handed three set points after a second successive double fault from her opponent, and the American held her nerve to draw first blood.
Sabalenka looked short on ideas throughout, and had no answer to the depth and pace on the forehand coming from the opposite side of the net as she was broken with her first service game in the second set.
The quality of points from Anisimova continued to flow and she will now face the winner of Petra Kvitova's clash with Belinda Bencic for a place in the quarter-finals.
Anisimova can barely contain her joy after securing the win
Image credit: Getty Images
"It's an unreal feeling. I cannot believe this is happening right now," Anisimova told Eurosport.
"I was expecting a really tough match, she's a great player, so I really can't believe I got through this round.
'I'm feeling great out here and I am really playing some good tennis."