Novak Djokovic was in ominous form on the opening day of the ATP World Tennis finals in London, handing the talented Japanese Kei Nishikori a brutal lesson in hardcourt tennis.
The Serb launched his bid for a record fourth successive title at the Finals with a 6-1 6-1 trouncing of Nishikori to extend his unbeaten run on indoor hardcourts to 38 matches over more than three years.
Djokovic has round robin matches to come against Roger Federer and Tomas Berdych.
Meanwhile, the Czech Republic defended its Fed Cup women's tennis title with a thrilling 3-2 victory over Russia as Karolina Pliskova won her singles match then returned to the court to help secure victory in the deciding doubles in Prague.
The Czechs, who claimed their fourth Fed Cup triumph in five years, fell behind 2-1 after Russia's Maria Sharapova defeated two-time Wimbledon champion Petra Kvitova 3-6, 6-4, 6-2 in the opening match of the day.
Pliskova then tied the final after cruising to a 6-3, 6-4 victory over Anastasia Pavlyuchenkova as the Czech's service game and punishing forehand were too much for the Russian to handle.
The Czechs claimed the title with a win in the doubles when Pliskova and Barbora Strycova bounced back after losing the first set 4-6 to Elena Vesnina and Pavlyuchenkova to take the next two 6-3, 6-2 in front of a boisterous home crowd.