Greek Australian tennis champion, Nick Kyrgios beat reigning champion Daniil Medvedev 7-6 (11) 3-6 6-3 6-2 in their round of 16 match at the US Open.

Kyrgios began strong and claimed the first break only for Medvedev to break straight back.

Kyrgios fended off two set points in the tiebreaker to win 13-11 and an end an engrossing first set.

After such a brilliant start, the second set saw both players take the foot of the accelerator with Kyrgios broken in the second game before Medvedev himself stumbled late on only to win the set 6-3.

The third set saw the intensity pick up with Kyrgios on the front foot early and he made an incredible error with a break point begging as he crossed the net to play at a ball that was going out from Medvedev.

Despite the brain fade, the Greek Malay Australian won five straight points two games later to break his Russian opponent and run away with the set 6-3.

Keen to avoid a five-set match, Kyrgios broke Medvedev twice in the fourth set as he played some of his best tennis and got the crowd on his side as he strolled to victory inside three hours.

Kyrgios will now face Russian Karen Khachanov in the US Open quarterfinals with Medvedev set to lose his number one ranking because of his exit.