The French Open, which begins quarterfinal play today, has traded its warm spring weather for an October chill that has affected more than just the players' wardrobes.

Why it matters: Neither Roland Garros' signature clay courts nor a standard tennis ball is weather-resistant, and the altered interplay between the two has required players to adapt on the fly.

• The "clay" is actually a 0.08-inch layer of crushed brick atop a limestone and gravel foundation. Due to the increased elasticity and friction, balls bounce higher and spin more on clay than other playing surfaces — but damper weather mitigates those effects.
• The ball is simply subjected to the laws of physics, whereby colder weather decreases its kinetic energy and increases air density, causing it to bounce less and travel slower.

The big picture: Rafael Nadal is the greatest clay court player ever, going 12-0 in French Open finals thanks to a lethal combination of elite athleticism and the world's best topspin shot.

• Yes, but: Those two advantages are somewhat neutralized by cold weather, meaning the preternaturally talented Spaniard will need to reach deeper into his bag of tricks to earn a 13th win at Roland Garros.

What to watch: Nadal sits one Grand Slam shy of tying Roger Federer's record mark of 20, and he's two wins from reaching the final."The later in the year, the lower the bounces. You have a slower court, slower balls, heavier conditions over all. Rafa doesn't like that. He likes a sunny, dry day and a high bounce."

Hall of Famer Martina Navratilova, via NYTToday's slate:

• Men's QF: No. 12 Diego Schwartzman vs. No. 3 Dominic Thiem (8:25am ET); No. 2 Rafael Nadal vs. Jannik Sinner (11:20am)
• Women's QF: No. 3 Elina Svitolina vs. Nadia Podoroska (7:15am ET); Iga Świątek vs. Martina Trevisan (10:05am)

Pre-match reading:

• Meet the unlikely French Open women's quarterfinalists (ESPN)
• Beware of Diego Schwartzman, a tennis David in a sport of Goliaths (NYT)