- Tag results for Jack Sock
Team World's Jack Sock and Kevin Anderson needed a tiebreaker to defeat the doubles dream team of Federer and Djokovic 6-7, 6-3, 10-6.
The pair won its second straight Grand Slam doubles title together, beating Lukasz Kubot and Marcelo Melo 6-3, 6-1
Jack Sock became the first American to reach the semi-finals of the season-ending event since Andy Roddick in 2007.
Roger Federer made a strong start to his bid to cap his golden year as the Swiss star defeated Jack Sock on Sunday.