With just two weeks remaining in the tennis season, five players have already locked up spots in the World Tour Finals at the O2 Arena in London. Rafael Nadal, Novak Djokovic, Roger Federer, and Stanislas Wawrinka have earned enough points that they cannot fall out of the top eight, no matter what happens.

Marin Cilic is currently sitting at No. 6 in the Race, 115 points behind No. 5 Kei Nishikori. However, Cilic is guaranteed a spot due to a rule that has not been necessary to use since 2005. If one major winner does not finish in the top eight but does finish in the top 20, he will earn a spot in the World Tour Finals regardless. (If multiple Grand Slam winners finish outside the top eight, only the highest-ranked player qualifies using this method.) Cilic could, in theory, finish as low as No. 11 in points earned in 2014. However, since that is within the top 20 and he won the US Open this year, he has already qualified for London.

That means there are exactly three spots remaining for a World Tour Finals berth, and the competition for them is intense. The final two weeks of the year are often drama-packed as contenders for the Finals can either rise to the occasion or wilt under the pressure of booking themselves a spot. With simultaneous ATP 500 tournaments this week in Basel and Valencia, and a Masters 1000 in Paris to close the season next week, there are a lot of points available for a relatively tightly packed group of players.

Currently, there remain six players mathematically capable of earning those final three spots. And, in what makes this end to the season even more special, every single one of them controls his own path to the Finals.

Kei Nishikori (4265 points)- Nishikori looks like he has a solid cushion right now, but things could get very dicey at the end of the week. He is not playing either Basel or Valencia, which means that he could in theory fall to the seventh and final qualification position by the end of the week (if Murray or Ferrer defeats Berdych in the Valencia final) with only a minimal lead over eighth place. Then again, if other contenders stumble, he could be all but guaranteed his spot by the end of the week. Either way, as of right now, a runner-up showing next week in Bercy will clinch it for him.

Tomas Berdych (4150 points)- Berdych did himself a huge favor by winning Stockholm and has a favorable draw to reach the final (at least) in Valencia. He has already played four ATP 500 tournaments this year and has a lot of Davis Cup points, so he cannot count full points this week, but a win or runner-up this week will put him in very good position. He can clinch a spot with a runner-up in Bercy or a win this week and a Bercy semifinal.

Andy Murray (3885 points)- Murray's three-set victory over Ferrer in the Vienna final moved him into the final qualifying position for the World Tour Finals for now. He is in danger of not reaching the Finals for the first time since 2007, and a potential rematch with Ferrer in the Valencia semifinals looms. He can clinch a Finals spot with a win in Bercy or a win this week and a semifinal in Bercy.

David Ferrer (3775 points)- Ferrer lost a heartbreaker last week against Murray, but he can't let that get him down, especially since he will probably get a chance for revenge–at his hometown tournament to boot. He can clinch a Finals spot with a win in Bercy or a win this week and a runner-up in Bercy.

Milos Raonic (3795 points)- Raonic trailed Ferrer by only 25 points to start the week but is playing in Basel this week instead of Valencia. Valencia has a higher average player, but Basel has more star power at the top. This means that while early upsets are more likely at Valencia, it will be harder for Raonic or Dimitrov to pick up the big points for winning or reaching the final in Basel. Raonic got a favorable draw but could still meet Nadal in the semifinals. He can clinch a Finals spot with a win in Bercy or a runner-up this week and a runner-up in Bercy.

Grigor Dimitrov (3555 points)- He is the last player still alive, although he trails by a considerable margin and has a very tough draw in Basel. He can clinch with a quarterfinal this week and a win in Bercy.