Karen Khachanov defeated Learner Tien in the fourth round of the US Open in a five-set thrilling contest to advance to the quarterfinals of the tournament on Monday. Khachanov claimed a 7-5, 4-6, 6-7(6), 6-1, 6-4 win in a hard-fought battle, which lasted for three hours and 50 minutes in New York.

The Russian admitted it was a crazy match, as he had to dig deep. Tien was leading by two sets to one, but Khachanov had the last laugh.

“It was a really crazy match,” said Khachanov. “We played for the first time against each other. I knew what to expect: One extra ball coming back, one extra ball. So many close rallies. He loves to play that defense outside the court, that’s why it makes it extremely tough, this match, because you have to stay always in the match with great intensity, hitting, hitting, pushing. In the end, I’m super happy that I could pull through.”

Khachanov entered the New York major with a 0-3 record throughout this year’s North American hard-court swing, but he has been able to turn a corner in the final Slam of the year.

Khachanov revealed that he decided to put in the extra work, which is paying off at the US Open.

“When you are not playing well or not having good results, you have to try to stay ready for the next one,” said Khachanov. “I was getting more fit. I was practising quite a lot and look, it paid off. It’s paying off slowly.”

Khachanov will next take on 28th seed Alexander Blockx in the quarterfinal clash.

On the other hand, Tien was looking to become the youngest American men’s quarter-finalist in New York since Andy Roddick in 2002 but it wasn’t to be for the youngster.