New York: Australian maverick Nick Kyrgios sent defending champion and world number one Daniil Medvedev crashing out of the US Open in an explosive last-16 clash on Sunday.Wimbledon runner-up Kyrgios triumphed 7-6 (13/11), 3-6, 6-3, 6-2 to reach his first quarter-final in New York where he will face another Russian, Karen Khachanov.Medvedev will lose his world top ranking after being defeated by Kyrgios for the fourth time in five meetings.Kyrgios fired 21 aces and a total of 53 winners past his outclassed Russian opponent.“It was an amazing match, obviously Daniil as the defending champion had a lot of pressure on his shoulders, but I’ve been playing amazing the last couple of months,” Kyrgios said after the win.“What a place to do it — packed house in New York. I’m extremely blessed.“Losing the Wimbledon final was a bitter pill but now I want to go all the way here.“I’m glad I can show my talents — it’s only taken me 27 years.”Italian Matteo Berrettini reached his second consecutive U.S. Open quarter-final by winning a marathon battle with Alejandro Davidovich Fokina 3-6 7-6(2) 6-3 4-6 6-2 on Sunday after the Spaniard suffered an injury in the final set. 23-year-old Casper Ruud, seeded fifth, will face Berrettini for a place in the semi-finals.Casper Ruud became the first Norwegian man to reach the US Open quarter-finals on Sunday with a 6-1, 6-2, 6-7 (4/7), 6-2 victory over French lucky loser Corentin Moutet.