Jack Sock claims comeback win over Marin Cilic to keep ATP Finals hopes alive

Jack Sock kept alive his hopes of reaching the ATP Finals knock-out stages by beating Wimbledon runner-up Marin Cilic in a final-set tie-break.

Cilic had thrown away a break in the decider to lose against Alexander Zverev on Sunday and he managed the same again at London's O2 Arena as Sock fought back to win 5-7 6-2 7-6 (7/4).