Rafael Nadal’s triumph at this year’s United States Open reinforced the argument that he might be the greatest men’s tennis player ever — outdoors.
It’s a small but notable distinction on the eve of the Paris Masters and the ATP Finals. Nadal loves Paris in spring, winning a dozen French Opens, yet he has never won the indoor Masters 1000 tournament just across town. Nor has he ever captured an ATP Finals title, which is also played indoors.
This is partly because Nadal grinds so hard that his body wears down by year’s end. Last year he withdrew from the Paris Masters and the ATP Finals because of an abdominal injury; the year before, a knee injury ended his season in the Paris quarterfinals; and in 2016, he was out with wrist woes.
But indoor tennis is different enough to negate some of Nadal’s brilliance while allowing others to thrive. It’s an environment that helps servers pinpoint location and be more aggressive, and it favors players who like to attack early or counterpunchers who hit flat.
In other words, there’s a reason the topspin-reliant Nadal has made just one final at the Paris Masters and two at the ATP Finals, while Roger Federer (one of the best servers ever and the most aggressive of the game’s elite) has reached the final of the ATP Finals 10 times, winning six, and Novak Djokovic (the ultimate defender who hits flat shots through the court) has reached seven of those finals, capturing five titles.
The most obvious difference indoors is the lack of sun and wind, which allows servers to toss the ball where they want it. “If you have a huge serve, you can be more aggressive indoors,” David Macpherson, who coaches John Isner, said via email.
Ivan Ljubicic, the former world No. 3 who now coaches Federer, said in an email some intangible factor helped with serving indoors, even if he could not precisely pinpoint it.
“We can say a night session outdoors without wind is the same, but it is not,” he said. “I think there is something to do also with the roof above as a reference for a ball toss.”
There are nuanced differences indoors, like increased crowd noise and echo, which can pump up or unnerve a player, MacPherson and Ljubicic both said. That added noise can also slow players’ reactions.
“People don’t realize how much players rely on sound to judge the speed and where on the racket your opponent hit the ball,” said Bethanie Mattek-Sands, winner of five women’s doubles Grand Slams. “It takes a little adjustment.”
The major difference is the way the ball bounces — or rather, doesn’t. Paris, which was exceedingly fast until 2011 when tournament officials changed the makeup of the court, still plays quicker than the ATP Finals at the 02 Arena in London, MacPherson added, although indoor courts are all slower than they were decades ago.
Then, on what Brad Gilbert, an ESPN analyst, called the “crazy fast” surfaces (including carpets), “big servers dominated indoors. There wasn’t a lot of tennis played because the points were so short.”
Contemporary indoor courts provide better tennis, but have what MacPherson called a deadening effect on the ball, which he and Ljubicic both said neutralized the kick serve, which was, for years, Nadal’s favorite weapon against many players, especially Federer.
“On the second serve, the advantage really goes to the returner,” said MacPherson, who added that the wind outdoors, combined with kick or spin, can make teeing off on a second serve more challenging.
Ultimately, Isner argued, arena conditions help big servers like him less than his opponents. “It makes a bigger difference for the really good ball strikers to have no wind and can hit the ball so cleanly,” he said. “It favors quick players who can counterpunch.”
Ljubicic partially agreed, saying that without wind, the slow, low-bouncing courts make it difficult to beat great movers who can control the ball. He cites Djokovic as the prime example.
Djokovic, unlike Nadal, hits fairly flat shots that penetrate the court. “Players that hit flatter have an advantage,” MacPherson said. “By contrast, a player like Nadal finds it hard to use his excessive topspin because he can’t get the same bounce.”
Ljubicic said players should capitalize on conditions by becoming more ambitious. “Aggressive players with less margin for error benefit inside where there’s no wind, which is why Federer is so spectacular because he can take the ball early and play offense,” said Paul Annacone, a Tennis Channel analyst.
Federer leads active players in winning percentage indoors, trailing John McEnroe, Ivan Lendl and Jimmy Connors. Those three played more indoor matches — 496, 411 and 595, respectively, compared with 360 for Federer. (Indoor statistics do not count Grand Slam matches under closed roofs.)
Today’s ATP Tour has just 16 indoor tournaments, and most are too small to attract elite players. Beyond the ATP Finals and the new Laver Cup, there are just three ATP Masters 500 level tournaments. Paris is the sole indoors Masters 1000 tournament. (The clay court season features three Masters 1000 battles.) By contrast, in the 1970s and most of the 1980s three or four Masters 1000 equivalents were held inside, and until 2008 there were always at least two.
According to ATP statistics, Federer is 292-68 indoors, for an 0.811 winning percentage, which nearly equals his outdoor mark of 0.824. That rates him better than Djokovic, whose indoor mark is 0.781 compared with 0.836 outside. By contrast, Nadal has just an 0.681 indoor winning percentage, compared with 0.848 outdoors.
Other top active players, including Andy Murray, Kei Nishikori, Jo-Wilfried Tsonga, Gael Monfils, Marin Cilic and David Goffin, actually have higher winning percentages indoors than out.
Gilbert said that with 2019’s year-end No. 1 ranking possibly coming down to these two tournaments, Djokovic had a major advantage over Nadal. Of course, there are other contenders in Paris and London beyond Djokovic and Federer. Daniil Medvedev, who has quickly risen to fourth in the world, is a big server and a counterpuncher who moves well and hits relatively flat, Gilbert said. “That translates well indoors.”
Annacone added that Medvedev’s high tennis I.Q. and ability to switch styles should also benefit him. Medvedev is 12-1 indoors, with two titles in 2019, the best indoor record this year. Annacone also cited Karen Khachanov, the defending Paris Masters champion; Alexander Zverev, last year’s ATP Finals champion; and Stefanos Tsitsipas as players to watch.
Nadal has complained for years that the ATP Finals, which is the most important tournament after the Grand Slams, should occasionally be played outdoors or on clay. However, Pam Shriver, an ESPN analyst, said the indoor showdown made a fitting finale.
“It feels more like the main stage of a theater,” she said. “And with no variables indoors, it should produce the highest quality play, which is good for tennis and good for the fans.”