WIMBLEDON, England — “Times have changed,” Roger Federer said this week as he looked back on his early days at Wimbledon.
Serve-and-volley was the rule then for the men, not the exception. Points were shorter, but the shots often slower. Modern string and racket technology and modern training methods have helped all professional players generate more pace and spin from extreme positions, and no shot better exemplifies the shift than the one the 39-year-old Federer has popularized over the course of his 23-year professional career.
It is best known as the squash shot, in part because Federer played squash in his youth, and it is a lunging forehand slash, typically from an open stance.
It is a spectacular shot to watch and, as Federer once told me, “a very fun shot to hit.”
But it is not typically good news when you have to use it.
“Honestly, it’s your last-resort play,” said Mackenzie McDonald, a 26-year-old American. “Maybe your only option.”
But in tennis, players adjust to the challenge and the risk. As pro tennis has accelerated, they have created new ways of defending, and the squash shot has become a staple through the years, perhaps even more in the women’s game than in the men’s.
“For me, that’s a sign of the influence of Fed across the whole sport,” said Brad Gilbert, the ESPN analyst and former top-five player, referring to Federer.
Barbora Krejcikova, a versatile all-court player, put the squash shot to frequent and excellent use on clay in her surprise run to the French Open title last month. The French veteran Alizé Cornet deployed it in winning an acrobatic match point in the first round of Wimbledon against Bianca Andreescu, who likes the squash shot, too.
On Friday, Ons Jabeur, perhaps the craftiest of all the new women’s stars, used it on match point in her third-round victory over Garbiñe Muguruza on Centre Court. Muguruza, a relentless hitter, struck a backhand down-the-line with authority. Jabeur stretched to her right and chopped a forehand crosscourt to get herself back into a rally that she ended up winning.
“So many players are doing it now,” said the ESPN analyst Mary Joe Fernandez, a two-time Grand Slam singles finalist and former Fed Cup captain. “It’s a great-looking shot and effective most of the time, because it’s a hard, good slice and it stays low. It’s an added shot. It’s definitely one I didn’t have and one I don’t think my generation had. But it’s a way to sustain the point, and more often than not, it works.”
Players also use it as a change-of-pace passing shot. Anastasija Sevastova called on it often in her victory last month over Elena Rybakina in the quarterfinals of the grass-court Eastbourne International. Rybakina repeatedly made volleying errors off the shot.
“It throws players off guard,” McDonald said. “I feel it’s actually harder to hit a volley off a slice than a ball with topspin.”
The forehand slice has been around since the beginning of lawn tennis. It is the best way to hit a forehand drop shot, of course, but it also was long the favored method for approaching the net. The forehand slice stayed low and often skidded away from the opponent, making it difficult to hit a solid passing shot, particularly with the wooden rackets and gut strings of yore.
But the racket frames are carbon-fiber weapons now and, most important, the strings are made of polyester, allowing players to take huge cuts at the ball, even when off-balance, and still create the spin necessary to drop the ball at a net rusher’s feet with topspin. The technology can also help them hit a low, firmer slice with both the backhand and the forehand.
“Good luck hitting that shot at full stretch with gut string and a wood racket,” Gilbert said of the squash shot. “You are making that once a Christmas.”
Though pros normally lobbed from that extended position in Gilbert’s era, players did use a version of the squash shot in the past. The Australian greats Roy Emerson and Rod Laver defended with a sliced forehand on occasion. Paul Annacone, a former top-20 player who coached Federer, said he recalled the Swedish pro Mikael Pernfors hitting forehand slices on the run in the 1980s and the early ’90s.
But Pernfors was an outlier. The difference now is how much firmer the shot feels and looks and how well it can be controlled. Even with tremendous racket head speed and with a need to sometimes adjust the forehand grip on the stretch.
“Every time I hit it, I am amazed that it actually stays in,” Federer once said.
The surprise factor has clearly worn off, and skeptics have become believers.
“When I first saw Fed do it, I thought it only works for a genius like him,” Gilbert said. “But after seeing Daniil Medvedev and so many others use it, I had to re-evaluate. It works much better than I thought, and it’s the poly strings that allow players to make that tomahawk swing and still be able to hold the ball and keep it in the court. It’s an even harder slice than the one-handed backhand.”
Gilbert sees players reconfigure points with it, turning an extreme defensive position into something closer to an offensive one.
“I’m cured, it works,” Gilbert said with a laugh. “You see guys in control of a point suddenly asking, ‘What just happened?’”
Gilbert said he remained unconvinced about another newly popular shot, the between-the-legs, back-to-the-net “tweener” that players often use after tracking down lobs.
“It looks brilliant, but I still don’t think it’s as effective as throwing up a lob or running around it,” he said. “But the squash shot is a lot more viable. I think it is here to stay.”
McDonald, a former U.C.L.A. star in the midst of a resurgent season, has practiced often with Federer, even traveling to Dubai to train.
“It’s funny in practice because he’s always playing, working on those shots that wow people,” McDonald said. “He’s always practicing those hand skills that wow you. When you see him hit a squash shot or a drop shot winner off a return, he actually practices those things, sometimes just for fun. But that’s why he’s come up with those shots through the years, because he’s always testing things out. He’s different in that sense than a guy who is just banging out a bunch of forehands and backhands in practice. He’s always sharpening his hand skills.”
But though the rise of the squash shot will be part of Federer’s legacy, McDonald said his inspiration for making it part of his arsenal was actually not Federer. It was Steve Johnson, a 31-year-old American player currently ranked 74th in the world.
“I might have used it some in college, but being on tour, you are trying to find that one percent difference and having that squash shot is maybe part of that one percent,” McDonald said. “Stevie Johnson was one of the guys who really hit it well. I’ve seen him hit dart-like winners off it. When you see that, you want to do it, too.”
So it goes in tennis as the times and the tactics change.
