The 28-year-old Japanese is making a late charge to the eight-player ATP Finals, in what would be his first appearance in two years when it opens in London on November 11. But reaching Sunday's final, his third of the season, boosted the fifth-seeded Japanese's chances of also advancing to the ATP finals.
In the process, Anderson booked his place for the Nitto ATP Finals in London next month joining Rafael Nadal, Novak Djokovic, Roger Federer, Juan Martin del Potro and Alexander Zverev for the season-ending event.
Anderson, who has now won five ATP titles, said it had been his goal all year to qualify for the ATP Finals.
Thanks to his powerful serve, Anderson, who fired 13 aces, managed to save two break points he faced, while he only managed to break his opponent's serve once out of seven opportunities he created.
After pushing for the break in the decider, Anderson finally converted on his sixth break point opportunity of the set to seal the win in the final game.More news: Pakistani court overturns Christian's death sentence for blasphemy
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Kevin Anderson with his winning trophy at the ATP Erste Bank Open 500 in Vienna.
His victory is the latest in a dream year for South Africa's top-ranked singles tennis player after reaching his second career Grand Slam final at Wimbledon.
In Switzerland, Federer moved a step closer to a ninth title albeit he was out of sorts in his 7-6 (7-1) 4-6 6-4 beating of Gilles Simon.
He clinched on his fourth chance when Medvedev netted from the baseline.
He improved to 2-3 in finals this year after the 32-year-old won the inaugural New York Open in February.
Anderson's success in Vienna was the biggest of his career to figure in the ATP Top 10 for the first time.