LONDON -- Fourth seed Daniil Medvedev came from one set down to edge world No. 3 Dominic Thiem to claim his first ATP Finals victory here on Sunday.

Just as he did in Saturday's semifinal where he came from one set down to knock out world No. 2 Rafael Nadal, Russia's Medvedev showed great resilience in beating Thiem 4-6, 7-6 (2), 6-4 in the final.

"It can give me a lot for my future career, I mean, to beat Dominic the way he played today is probably the best victory of my life. Not even talking about the title itself," said the 24-year-old, who had lost all three group matches in last year's ATP Finals.

Earlier in this year's group stage, Medvedev had defeated world No. 1 Novak Djokovic in straight sets, meaning the Russian defeated the year-ending tournament's top three seeds.

"It means a lot. It shows what I'm capable of when I'm feeling good mentally and physically," said Medvedev.

After 12 years in London, the ATP Finals will be staged in Turin, Italy beginning next year.