Co-Workers: What Serena Williams and Novak Djokovic did so well in 2015

When Novak Djokovic beat Roger Federer to win his fourth straight ATP World Tour Finals title, he capped one of tennis’ all-time great seasons in appropriately fine style. But his win was appropriate for a second reason: It capped an all-time season of dual-gender dominance.

Djokovic and his fellow No. 1 on the women’s side, Serena Williams, made 2015 a year of historic individual achievement. In January, when they opened with titles at the Australian Open, some of us jokingly wondered whether they might both be on their way to winning calendar-year Grand Slams. We had no idea how close we were to being right. The co-Slam had never been done, and seemed unthinkable at the time, but Djokovic and Williams would fall just three matches short of pulling it off.

Serena and Novak aren’t the game’s first set of peerless pairs. In 1984, John McEnroe went 82-3, while Martina Navratilova won three majors. Four years later, Steffi Graf and Mats Wilander went them one better: She won the Golden Slam (all four majors plus an Olympic singles gold) while he won three Slams. More interesting, though, may be the traits that each of these sets of co-legends shared.

McEnroe and Navratilova were left-handed, hotheaded, and perhaps the two most gifted net-rushers of all time. Through the late 70s and early 80s, each fought against, and ultimately vanquished, an icier, more popular baseliner (Chris Evert for her, Bjorn Borg for him). Graf and Wilander marked the return of the icy baseliner in the mid-80s. By their peak year of ’88, the German and the Swede had made themselves into stoical winning machines.

On the surface, Djokovic and Serena don’t seem to have as much in common, as players, as Mac and Martina and Mats and Steffi. Serena is the best attacker in the women’s game, while Djokovic is the best defender among the men. But if you watched them, day by day and victory by victory, over the course of 2015, you saw a striking similarity in the way that the American and the Serb battled, and the way that they won.

There are steadier competitors than Serena and Djokovic. Maria Sharapova and Rafael Nadal are relentless in their efforts, and relentlessly positive in their outlooks. Roger Federer is a domineering force who competes in a self-assured style. Djokovic and Serena, by contrast, aren’t always so relentless, or so confident. They can lose belief. They can be seized by nerves. They can let their emotions get the best of them. Despite going a combined 135-9 in 2015, both suffered through their share of sluggish starts, mid-match funks, and stumbles at the finish line. Djokovic’s hand shook so badly in the Indian Wells final against Federer that he could barely get a bottle of liquid to his lips. Serena blew such a big lead in the French Open final that she flatly admitted afterward, “I choked.”

Tennis players are taught to compete stoically and tenaciously, to fight for every point with a level head and a killer heart, and never to let their opponents see them sweat. Serena and Djokovic often break these rules. Sometimes, when things don’t go their way, the stresses of competition can seem too be too much for them, and they aren’t afraid to show this to the other player. Yet once they feel that a set or a match has essentially been lost, and they can throw caution to the wind and let their shots rip, they become dangerous again. Serena and Djokovic are both known for saving match points and making back-from-the-brink comebacks, and that’s a product of their style of competing. Once they’ve gotten their nerves and their emotions out of the way, Djokovic and Serena are two of the deadliest ball-strikers in tennis history.

All of which makes their 2015 seasons seem that much more exceptional. It’s one thing to coolly and relentlessly dismiss opponent after opponent, the way Graf did in her prime. It’s another to master your own volatile emotions day in and day out, the way Djokovic and Serena did in 2015. I’ve never seen two players who are better at succumbing to nerves for a brief period, and then putting those nerves aside and winning—often 6-0 or 6-1 in the final set—in spite of them. Despite their otherworldly records this year, these are two champions who make valuable models for the rest of us. We all know what it’s like to be seized by anxiety; Serena and Djokovic show us that it’s possible to control it, and defeat it.

Maybe it’s fitting that both of our No. 1s were dominant in 2015, but not quite perfect. Djokovic went 27-1 at the majors, Serena 26-1. In their struggles against themselves, and their willingness to show us their vulnerabilities, these remain two of tennis’ most human champions, and that makes their superhuman achievements in 2015 all the more remarkable.

Originally published on Wimbledon.com.