US Open: Nick Kyrgios gives away point to Daniil Medvedev with ridiculous penalty

Nick Kyrgios faced a chance to break Daniil Medvedev in the third set of their fourth-round US Open showdown on Sunday.

Instead, he did this.

After having a point secured when Medvedev popped up a return short of the net, Kyrgios crossed over to Medvedev's side of the court and slammed the ball to the ground. He then pointed in the air and smiled.

Why? Only Kyrgios knows. But he appeared to take great pleasure in the move.

It was illegal, of course. You can't hit an opponent's ball before it crosses the net, even if it's never going to cross the net. The move ended up costing him the point. Instead of facing break point, Medvedev served for the game leading 40-30. He converted and tied the set, 1-1.

After a break, ESPN's Patrick McEnroe reported from the sideline that Kyrgios told him that he thought the play was legal. But he didn't seem at all upset about the penalty. Instead he continued to complain to chair umpire Eva Asderaki-Moore about her enforcement of the serve clock, a conflict that started in the first set.

The good news for Kyrgios is that the point didn't cost him. He ended up breaking Medvedev's next serve and went on to win the set, 6-3 to take a 2-1 lead in the match en route to a 7-6 (13-11), 3-6, 6-3, 6-2 win to stun the world's No. 1 player and advance to a quarterfinal match with Russia's Karen Khachanov.

Only Nick Kyrgios.