LONDON (Reuters) - A clinical Novak Djokovic thrashed Kei Nishikori 6-1 6-1 on Saturday to set up a season-ending winner-takes-all showdown with home favorite Andy Murray at the ATP World Tour Finals.

Shortly after Murray had triumphed in his semi-final against Milos Raonic, the longest match ever seen at the championships, defending champion Djokovic steamed past the lackluster Japanese in little more than an hour, hardly breaking sweat.

Djokovic, winner of the title for the past four years and one short of Roger Federer's six in total, lost his world number-one ranking to Murray earlier this month but will seize it back if he defeats the Briton in Sunday's final.

His win over Nishikori was his 22nd in his last 23 matches at the tournament he has dominated.

(Reporting by Martyn Herman,; Editing by Neville Dalton)