Japan's Kei Nishikori crashed out of the U.S. Open on Friday, losing his third-round match against Australia's Alex de Minaur.

The seventh-seeded Nishikori, still searching for his maiden Grand Slam title, suffered a 6-2, 6-4, 2-6, 6-3 defeat to world No. 38 de Minaur in the year's final major.

"He was playing great defense and I ended up making many errors. I think that is the main reason why I lost," said Nishikori, ranked No. 7 in the world.

De Minaur claimed his first win over a top-10 player and advanced to the fourth round of a Grand Slam for the first time.

"Going into this match, I talked to my team and we had a game plan. I'm very happy I was able to execute that game plan and play some good tennis," he said. "I fought very hard in certain points and I'm happy that I could finally get my first top-10 win."

Nishikori struggled from the beginning, committing a total of 59 unforced errors as compared to 29 by his opponent. A string of missed forehands cost him two early breaks in the first set, which he lost after de Minaur survived a triple break opportunity at 5-2 for the decisive hold.

In the second set opener, Nishikori handed his opponent a lead with a game-ending double fault. Though he managed to level at 4-4, de Minaur grabbed another break in the following game and served out for a two-set advantage.

Nishikori's only hope for a rally came in the third set, when he protected an early lead with a difficult hold to go up 4-1. Three games later, the 20-year-old Australian lost serve and the set with an ill-timed double fault.

But Nishikori's struggles returned in the fourth set, as he dropped a late break to love. He lost serve again in the final game with a series of errant shots, giving de Minaur the match in 2 hours, 48 minutes.

The 29-year-old Nishikori was competing in the main draw of the U.S. Open for the ninth time. He advanced to the final in 2014 and has reached the semifinals twice since.