Nishikori beats Wawrinka in straight sets at ATP finals

Kei Nishikori of Japan plays a return to Stan Wawrinka of Switzerland during their ATP World Tour Finals singles tennis match at the O2 Arena in London, Monday, Nov. 14, 2016. AP Photo/Kirsty Wigglesworth

LONDON  — Kei Nishikori improved his chances of finishing the season as the No. 3-ranked player, beating U.S. Open champion Stan Wawrinka 6-2, 6-3 Monday at the ATP finals.

Currently ranked fifth, the Japanese player managed to break Wawrinka twice in each set and start his round-robin group play with a victory.

Wawrinka is ranked No. 3 in the world, but he, Nishikori and Milos Raonic all have a chance to finish the season one spot behind Andy Murray and Novak Djokovic.

Murray will face Marin Cilic later Monday at the O2 Arena, taking the court as the No. 1-ranked player for the first time.

Djokovic can still overtake Murray and finish atop the rankings depending on this week’s results.