Rafael Nadal has revealed the secret conversation he had with Dominic Thiem after their US Open match.

Nadal met the Austrian in the quarter-finals of the US open, a tournament the Spaniard has won four times.

The world number one was remarkably bageled in the opening set, but recovered to win 0-6, 6-4, 7-5, 6-7(4), 7-6(5).

Nadal will now meet Argentine and world number three Juan Martin del Potro in the semi-finals, but the 32-year-old revealed the conversation he had with his Austrian opponent Thiem.

“I just said ‘I am very sorry. You are very good’,” Nadal said.

“He has plenty of time to win big tournaments and has everything. He is a fighter with a great attitude so that is the most important thing.

“He is a very well educated guy and a top person. I am sorry for him, but I am sure he will have his chances in the future, without a doubt.”

Nadal, who was on court for four hours and 48 minutes in a tie which finished at 2.04am local time in New York (7.04am BST), commented on the humidity of the playing conditions that has troubled so many players in this year's Open, and broke down his performance.

“It has been a great battle. The conditions were tough and very humid,” he said.

“It was a very tough start and then I tried to stay in the match in some way in that second set and I did.

“Then the third set happened - he served for the set - then I won two games in a row and took the set.

“In the fourth I had some chances in the beginning, didn’t convert, then at love-40 in the 5-4 broke my heart but I just kept going.

“Being honest I am just very, very sorry for Dominic. He is a close friend on tour and a great player.

“I just wish him all the very very best.”