MALAGA, Spain — Sara Errani stands at the baseline and exhales deeply. She is about to hit a second serve, with Italy up match point against Poland. A place in the Billie Jean King Cup final is at stake. So Errani does what she has done many, many times before: she hits an underarm serve.

The ball floats into the service box and onto the racket of Iga Swiatek, one of two women’s players who can claim to be the best in the world. Swiatek is on to it in a flash and hits her return deep to Errani’s forehand. Errani again does what she has done many, many times before: she gets the ball back.

She does the same on her opponent’s next shot, hoisting a backhand lob into the air. Swiatek loops a forehand volley long and Italy is through to the final for the second year in a row.

Errani collapses to the ground in relief, celebrating with her partner Jasmine Paolini and shaking hands with the defeated opponents a few seconds later, before allowing herself a what-have-I-just-done smile.

For Errani, 37, it was another successful heist in a career full of them.

On Wednesday, she added a fourth Billie Jean King Cup title (three of which came when it was the Federation Cup) to the career Golden Grand Slam in doubles she completed this year by winning gold at the 2024 Paris Olympics alongside Paolini. It has been a stunning year for Errani, who also won the mixed doubles title at the U.S. Open with another Italian, Andrea Vavassori. She thought 2024 would be her last on tour, having won her last major 10 years ago.

“My thought last year was to play in the Olympics and then stop playing tennis, but we’re playing great in doubles and I’m having so much fun,” she said in an interview in Riyadh, Saudi Arabia, at the WTA Tour Finals earlier this month.

Completing the doubles Golden Slam in Paris put Errani in an elite group of just seven women. When looking back on her career, the underarm serve to Swiatek on Monday will feel like a defining moment for a player who uses the contentious tactic more consistently and more particularly than anybody else.

Her story with the underarm serve goes to the heart of her tennis life.

The underarm serve is one of tennis’s most curious shots, caught between the poles of disrespectful trick shot and tactical masterstroke. Big servers like Nick Kyrgios can use it to take advantage of opponents who are standing back anticipating a 140mph rocket. There is an element of showmanship too; this is very much the case with Alexander Bublik. He might be blessed with a big serve, but he is also the current player probably most synonymous with the cheeky alternative.

Other players use it against specific opponents. World No. 68 Alexandre Muller told The Athletic at Wimbledon that he had specifically practised the shot to use it against Daniil Medvedev, who has one of the deepest return positions in the sport.

Corentin Moutet, a master of the shot, started practising underarm serves after a shoulder injury. He has since incorporated them into his game, doing so to great acclaim at this year’s French Open. He used the underarm serve 12 times in his third-round win against Sebastian Ofner, winning nine of those points. He is the opposite of a player like Kyrgios, using the underarm serve because he doesn’t expect to win free points behind his first serve; there is no drop-off in expected value.

Errani’s reason for using the shot will be familiar to many amateur players: she just doesn’t trust her serve.

Errani stands at 5ft 5in (164cm) which is diminutive by modern tennis standards — just like her partner Paolini, whose serve has some heat despite her height of 5ft 4in. Errani does not have this pace, and her height has contributed to a shot often derided as the worst serve in the sport.

Smiling, she says it would be amazing to be a bit taller. “Many times, I think about that.”

Instead of letting her serve become a complete albatross, Errani has used her ground skills, tactical nous and the shock factor of a serve that regularly registers around 60mph (96.5kph) on the speed gun to reach the very top of tennis in singles and doubles.

She reached the 2012 French Open final in singles and cracked the world’s top five a year later, despite her opponents feeling that they ought to break her every single game. Instead, they are bamboozled by her incredible dexterity at the net or from the back of the court, as well as struggling to read and return her serve.

Sara Errani has struggled with her regulation serve throughout her career (Thomas Samson / AFP via Getty Images)

“It comes so slow and it kind of floats in the air,” Mirjana Lucic-Baroni said in a news conference after losing to Errani in the 2014 U.S. Open fourth round, a match in which Errani’s average serve speed was 76mph.

“It was really difficult to time the balls.” Errani’s serve became something of a meme in 2024 after Daniil Medvedev completely failed to return it at all during a mixed doubles match at the Paris Olympics.

Errani herself said in a news conference after that match that she has a different approach to serving from most players: “I don’t try to make winners,” she said.

“I just try to make kick, make slice, try to change my game. I need to start the point where I want. So sometimes is better for me to serve not that fast, because if you serve fast the ball is coming (back) faster.”

That conviction hasn’t always been there. Her serve reached a nadir in April 2019 when she was only recently back from a 10-month doping suspension for ingesting letrozole, which was increased from an original two months by the Court of Arbitration for Sport (CAS). Errani said she was “really disgusted” by the length of the ban, saying that her case was because of contamination after her mother, who was taking letrozole for breast cancer, dropped pills on their kitchen counter where they prepared meals.

At the Copa Colsanitas in Bogota, Colombia, Errani served 18 double faults per match in three consecutive matches (all of which she won) before hitting around half her serves underarm in a quarter-final defeat to Astra Sharma. Later that year at a low-level event in Asuncion, Paraguay, Errani took the nuclear option by serving underarm for the entire tournament. She reached the final, copping a huge amount of social media abuse in the process.

In response, she wrote on Instagram: “In Italy, I keep being insulted by a lot of people, regarding mainly my serve.

“If it is not ok for you, send a letter to WTA asking to change rules about serve or ask them to disqualify me for awful serve. If instead you just have other problems with me, send a letter to Santa.”

Five years on, she says her serve had completely overtaken everything else.

“I couldn’t compete. I was thinking all the time about my serve,” she says.

“My coach said: ‘Do one tournament all underarm and just compete.’ It was to try to make my head free from, not panic, but the tough moments.”

Despite recovering from those yips, Errani then endured an anxiety dream of a service game at the 2020 French Open during a second-round defeat to Kiki Bertens. Errani was given two time violations after five aborted ball tosses and landed only one overarm serve, with one attempt missing the baseline. Serving for the set, she was broken to love.

“Sometimes it’s there and it can come out, but I try to manage it,” she says of the nerves that can grip her when serving.

“When I was practising, my serve was good. But then in matches, I was feeling the block, the panic. I know it’s still there. It’s not like it’s in the past.”

Errani, an unwitting trailblazer, can laugh at the fact that the underarm serve has come back into fashion, certainly on the men’s side, over the past few years. “If it can be a good tactic, why not?” she laughs. Against Swiatek, the decision was more of a vibe.

“I just advised Jasmine after the first serve, so it’s just I feel it and I did it, just like that, not thinking too much,” she said in a news conference after the match.

At 37, Errani is the Italian team’s most experienced player, and as her team-mates chorused in Wednesday’s celebratory news conference she is “the brain of the team”.

Errani resembles her compatriot Jorginho, the Brazilian-born Italy and Arsenal midfielder who is so intelligent that he is a reference point for everybody else despite not being the most physically gifted.

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Paolini, who is the world No. 4 in singles and a two-time Grand Slam finalist this year, constantly looks to Errani for guidance on the doubles court.

“She wants me to tell her what to do every point – even when she serves, she likes me to tell her where to put it and I’m trying to push her to tell me what she’s feeling more,” Errani said.

Sara Errani and Jasmine Paolini have formed a formidable partnership on the doubles court. (Robert Prange / Getty Images)

Whatever the tactics, the Errani-Paolini partnership is contributing to a golden period for tennis in Italy.

On the men’s side, Jannik Sinner is the world No. 1 and has won two Grand Slams this year. He is part of an Italy team that is hoping to defend the Davis Cup this week and make it a double with the victorious BJK Cup group. Errani, who lived through a period when she was one of the ‘Fab Four’ Italian women who all reached a Grand Slam final and the world’s top 10 between 2010 and 2014 (Francesca Schiavone, Roberta Vinci and Flavia Pennetta were the others), believes that all the current top players from her country are pushing each other to greater heights.

And Errani has no desire to leave the golden age behind just yet.  “I said to Jasmine: ‘I’ll continue next year for sure and then we’ll see,’” she says.

After the genre-defining underarm serve against Swiatek, this wily veteran still has at least one last heist in her.

(Top photo: Fran Santiago / Getty Images for ITF)