Anderson will be the first South African in 23 years to feature in the season-ending tournament in London next month after a 6-3 7-6 (7-3) defeat of Nishikori.

The towering 32-year-old is also guaranteed to finish the year in the top 10 for the first time, reward for claiming the fifth singles title of his career.

No.2 seed Anderson won 91 per cent of points behind his powerful first serve, Nishikori unable to fashion a break as his wait for a first title since February 2016 goes on.

A ninth successive tour-level final defeat struck a blow to Nishikori's hopes of returning to the ATP Finals, the Japanese former world No.4 sitting 325 points behind the eighth-placed Dominic Thiem ahead of the crucial Paris Masters.

Anderson broke in the fourth game of the match to lead 3-1 when a powerful backhand forced an error from the No.5 seed.

Nishikori was unable to find a way back in the first set and was consigned to defeat after Anderson's serve and forehand proved to be potent in a second-set tie-break, a 13th ace sealing the title.

Anderson joins Rafael Nadal, Novak Djokovic, Roger Federer, Juan Martin del Potro and Alexander Zverev in qualifying for the ATP Finals, with at least two spots up for grabs in the French capital next week.

It remains to be seen if Del Potro will be fit after he suffered a fractured knee.