The number 16 seed won 5-7, 6-4, 6-2, dumping the well-known Maria Sharapova out of the comptition in the process.
It is the second year in a row that Sevastova has made it through to the quarter finals.
"Despite Sharapova taking the driver's seat to start the match, Sevastova's crafty game left the former No. 1 puzzled as the match wore on," said the official website of the US Open, adding that Sevastova played "a near flawless match".
No.16 Anastasija Sevastova sends off Maria Sharapova 5-7, 6-4, 6-2 to return to the US Open QFs ?? https://t.co/BkelWHZgVj #usopen pic.twitter.com/eD6jR4sjDu
— US Open Tennis (@usopen) September 3, 2017
Sevastova now faces Sloane Stephens of the US in the quarter-finals having dropped just one set in the tournament so far.
A few interesting facts about Anastasija and a form guide can be found HERE.
Meanwhile, here's the winning moment.
TFW you return the US Open QFs for the second straight year. ? https://t.co/BkelWHZgVj #usopen pic.twitter.com/T6Q4Kgc4HU
— US Open Tennis (@usopen) September 3, 2017
(Note: it turned out to be a great match against Sloane Stephens, but unfortunately Anastasija lost on the tie break in the third set)