Jack Sock, a 23-year old tennis player from the United States, won hearts all round with an adorable display of sportsmanship during his Hopman Cup encounter against former Australian great Lleyton Hewitt in Perth.

Hewitt was trailing 4-5 in the first set and serving at 30-0. However his first serve was called "out" by the linesman. Unperturbed, Hewitt was preparing to take his second serve when a smiling Sock called over to him, "That was in if you want to challenge it."

Hewitt was baffled and took in his bearings for a moment, while the crowd cheered their approval at Sock's actions. After Sock urged him again to challenge it, Hewitt took the bait and called for the review. The review proved Sock right, showing that the ball was marginally inside the line.

Sock went on to lose the match 5-7, 5-6 but captured each and every heart.