The top threats to Nadal's Madrid title defense

As Rafael Nadal looks to extend his 19-match (46-set) clay winning streak, it seems all but inevitable that he will successfully defend his Madrid title for a record sixth career crown.

However, Madrid is, by Nadal's standards, one of his least dominant clay tournaments. He's lost there five times since the surface switched to clay in 2009.

Here are four contenders who might just do the unthinkable and take his title from him:

1

Dominic Thiem

Thiem, who had the misfortune of being drawn into Nadal's quarter, got crushed the last time he played the Spaniard—but, to be fair, so did every other player on this list. With his 2017 win in Rome, he's the last player to have beaten Nadal on clay, which has to be worth something, right? He's also the defending finalist.

2

Juan Martin del Potro

Though he's playing an abbreviated clay season, Del Potro is one of the hottest players on tour, second in the Race to London, and first discounting Roger Federer. He has only one career clay loss against Nadal (though they've completed only one clay match), and he's statistically equally as good on clay and hard courts. Still, the math of Nadal's forehand to Del Potro's backhand doesn't add up, so he best hope the lefty loses early.

3

Novak Djokovic

Djokovic has won this tournament twice before, and he's beaten Nadal in four of their last six matches on clay. Looking for his first big breakthrough of the season, he has the momentum of a first-round win versus Kei Nishikori, and the advantage of not needing to play Nadal before the final. He just may want to work on his smash between now and then.

4

Alexander Zverev

Coming off of a Munich title defense that included a win over Hyeon Chung, the 2017 Rome champion has a chance to solidify his status at the top. Should the No. 2 seed meet Nadal in the final, it may prove to much for the 21-year-old. Not only has he never beaten him in four attempts, but he hasn't gotten a set off of him since their five-setter at the 2017 Australian Open.

It's obvious that the tournament is in Nadal's hands. No player has a great a shot at beating him, so it'll come down to whether he can be on, or least good enough, for five matches in a row—again.

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