Novak Djokovic ensured he would end another year as world number one while adding another processional victory to a long list at the ATP World Tour Finals with his 6-2, 6-2 demolition of subdued Czech Tomas Berdych.

The Serb, virtually guaranteed a semi-final berth before walking on court at the O2 Arena, made doubly sure by cruising past Berdych in little more than an hour.

He will meet Japan's Kei Nishikori in Saturday's first semi-final before Roger Federer plays his Swiss compatriot Stanislas Wawrinka in the evening match, following Wawrinka's 6-3, 4-6, 6-3 victory over Marin Cilic.

A day after Roger Federer dropped only one game beating home favourite Andy Murray to win Group B, Djokovic was also in ruthless mood to top Group A and guarantee ending the year as world number one for the third time.

Seven-time grand slam champion Djokovic has now topped the closing standings for three of the last four years.

"To be able to stand next to this trophy and to have the crown for all the achievements in this 12 months, it's very fulfilling and it's a joy," Djokovic said after being presented with the year-end number one trophy in front of a parade of former world number ones including his coach Boris Becker.

"The tournament is not over. I have maybe a few hours of celebration and then turning back to the semi-finals and preparing for it."

Djokovic's 30th indoor victory in succession since the ATP World Tour Finals in 2012, lined up another meeting with Nishikori after the Japanese debutant finished second in Group B.

Source: Reuters