Novak Djokovic celebrates winning his tennis match against Tomas Berdych
Novak Djokovic of Serbia celebrates winning his tennis match against Tomas Berdych of Czech Republic at the ATP World Tour Finals at the O2 Arena in London November 14, 2014. Djokovic added another processional victory to the lengthening list at the ATP World Tour Finals with a 6-2 6-2 demolition of subdued Berdych on Friday. Reuters

Pressure is off Serbian Novak Djokovic after sweeping the group stage of the 2014 ATP World Tour Finals as he is now assured of ending up as the world number one in the year-end rankings. On Saturday night (Australia time), it’s now just the business of continuing to dominate indoor tennis with the tennis season finale set at the O2 Arena in London, United Kingdom. The Serbian will face Kei Nishikori of Japan in the semifinal round even as World No. 2 Roger Federer of Switzerland takes on compatriot Stanislas Wawrinka in the other final four match.

How Novak Djokovic and Kei Nishikori Reached the Semifinals

Seeded first, Djokovic has yet to lose a set in the London tournament with wins over Marin Cilic, 6-1, 6-1; Wawrinka, 6-3, 6-0; and Tomas Berdych, 6-2, 6-2. Nishikori, who became the first Asian to qualify for the season-ending finale in London or elsewhere, beat home country bet Andy Murray in the opener, 6-4, 6-4; lost to Federer, 3-6, 2-6 in his second match but recovered against replacement player David Ferrer of Spain in three sets, 4-6, 6-4, 6-1.

Djokovic’s performance has been expectedly impressive thus far winning a total of 36 games against just 9 games lost. Meanwhile, Nishikori proved his point early by beating Murray in London in what virtually became the deciding match on who advanced to the final four.

Novak Djokovic vs. Kei Nishikori Head-to-Head History

Surprisingly, Nishikori and Djokovic are tied with two wins apiece in their head-to-head match-up. The pair met for the first time way back in 2010 in the Round of 64 of the French Open with the Serbian winning in straight sets, 6-1, 6-4, 6-4. The Japanese tied the head-to-head the year after in the semifinals of the 2011 Swiss Indoors Basel with a three set victory, 2-6, 7-6 (4), 6-0.

It was only earlier this year when Djokovic and Nishikori met on the court again. Nishikori delivered a major upset in the semifinals of the 2014 US Open with a four-set victory, 6-4, 1-6, 7-6 (4), 6-3. In the lead-up to the finale in London and the final ATP World Tour Masters 1000 event in Paris, France, Djokovic made it 2-2 in their head-to-head series with an easy 6-2, 6-3 win in the semifinals.

Watch the ATP World Tour Finals Semis: Novak Djokovic vs. Kei Nishikori via tennistv.com or follow the action via the tournament’s official website’s Live Blog of the event.