The triumphal procession of Novak Djokovic to finishing the season as world No.1 reached journey's end last night in the O2 Arena.

The 27-year-old won his 30th consecutive match indoors by easily defeating Tomas Berdych 6-2, 6-2 to reach the semi-finals of the Barclays ATP World Tour finals where he will meet Kei Nishikori.

In doing so, the Serb clinched the No.1 ranking he has held at the end of three of the past four years and his athleticism is such that tennis may be on the verge of a Djokovic era of dominance.

He has not yet been stretched, though today's match-up with Nishikori will be intriguing because the Japanese defeated the world No.1 in the semi-finals of the US Open earlier this year.

The other semi-final will be contested by Roger Federer and Stanislas Wawrinka, who will be team-mates for Switzerland in the Davis Cup final next week against France.

A Djokovic-Federer final will be the deeply held hope of the organisers, after a tournament of two-set blowouts. A struggle between the greatest player of all time and the player who wants to be the greatest player of all time has the potential to give it the most dramatic of climaxes.