Stefanos Tsitsipas won the ATP World Tour Finals in 2019. (Getty Images)

The ATP Finals in London are getting underway on Sunday. Eight players have fought their way through one of the craziest seasons in tennis history to solidify their place in the draw. Novak Djokovic, Rafael Nadal, Dominic Thiem, Daniil Medvedev, Stefanos Tsitsipas, Alexander Zverev, Andrey Rublev, and Diego Schwartzman will fight for the title.

Last year, Tsitsipas took home the ATP Finals title after defeating Thiem in the final. The Greek is hoping to defend his title and be the first player to do so since Djokovic in 2015. Yet it might not be Tsitsipas who the fans will be focused on: Nadal, surprisingly, has still not captured the year-end title during his colorfully decorated career.

With the 50th ATP Tour Finals in London starting on Sunday, it's time to ask the question: