Medvedev grew frustrated in a four-set loss that ensured neither singles draws will have a repeat winner this year. Kyrgios will play another Russian, No. 27 Karen Khachanov, in the quarterfinals.
With another class win, this one over world No. 1 Daniil Medvedev, the Australian's reputation further evolves.
Nick Kyrgios will clash with Daniil Medvedev in a fourth-round blockbuster at the US Open. Read more here.
Nick Kyrgios is only into the US Open quarter finals after destroying world No.1 and reigning champion Daniil Medvedev - but he is in sight of his first Grand Slam triumph.
Fixture: (23) Nick Kyrgios vs (27) Karen Khachanov.
Greek Australian tennis star Nick Kyrgios has dethroned World Number 1 Daniil Medvedev after a blockbuster US Open showdown in New York on Monday morning
Nick Kyrgios and Daniil Medvedev are set to face off in an enticing round of 16 match at the US Open on Sunday night (local time).
A fired up Nick Kyrgios hammers a return to force a short reply from Daniil Medvedev, the Aussie pouncing on it for a second break of serve in the fourth set.