Nicolas Almagro had to defeat American youngster Jack Sock in four sets to progress through to the fourth round of the US Open at Flushing Meadows.

The 11th seed won a tough opening set 7-3 in the tie-break, but Sock, with the home crowd on his side, took the second 7-4 in another tie-break.

Under the intense New York sun, it took a third tie-break to get Almagro back in front, this time with a 7-4 scoreline.

However, it was far simpler for the Spaniard in the fourth as he broke three times to close out the match 6-1.