Ruminating on the Underhand Serve

Almost every sport has a set of unwritten rules that the competitors are expected to abide by and follow. In baseball, baserunners are discouraged from stealing bases in the late innings of a blowout. In American football, teams will often take a knee instead of running an offensive play if the game is already decided late in the fourth quarter. In soccer, a team in possession of the ball is expected to kick it out of bounds in order to allow medical treatment of an injured opponent. The application of the unwritten rules is nuanced and not universally agreed upon, even among the competitors themselves. The common thread among all these “agreements” though, is showing a level of respect for the opponent and the sport.

There are numerous examples of unwritten rules in tennis. For example, tennis players are expected to avoid trying to aim at their opponent with the ball during a rally, if there is an option to go around them. They are expected to apologize after they hit the net tape with a stroke, and the ball rolls over onto the opponent’s side. Players shake hands at the end of the match, regardless of how heated the competition might have gotten.

And then there is the underhand serve.

This is Dominic Thiem’s second serve return position in his third round match in the ATP Masters 1000 in Rome against Lorenzo Sonego:


I’m certainly not picking on Thiem. There are plenty of other players, who prefer to hit their returns from way behind the baseline: Rafael Nadal, Daniil Medvedev, and Stefanos Tsitsipas all come to mind. The reason for this is purely tactical; it gives them more time to react to the serve, potentially hit a forehand on the return, and gain the upper hand in the rally.

If you knew nothing about tennis, you might think to yourself: if my opponent wants to return from that far back, it would seem logical for me to try and entice them to return from closer to the baseline. Just like if my opponent wants to hit more forehands, I will aim at her backhand. I am trying to get my opponent to do the things they are not comfortable doing on the court.

You do have a potential weapon in your arsenal to help you accomplish just that: the underhand serve. But you’re not supposed to use it. Take a look at the reaction Nick Kyrgios got from Nadal when he used the underhand serve during their Wimbledon encounter in 2019:

Regardless of the history between Nadal and Kyrgios, the underhand serve is regarded as a sign of disrespect towards the opponent; they are “not worthy” of you hitting a “proper” serve against them. I would argue that the underhand serve could become a legitimate tactic in an era where, especially on clay, many players choose to set up for the return way back behind the baseline. What would have to happen for the underhand second serve to become less taboo? I think either of the following three developments would speed up the process.

A Respected Ambassador

If someone like Nick Kyrgios or Alexander Bublik decides to serve underhand, the stigma associated with that shot is reinforced. They are “young and brash,” “disrespecting the opponent and the game,” and “immature.” Both Bublik and Kyrgios are known for having tanked matches, and making eyebrow-raising statements in some of their post-match press conferences; their underhand second serves are then viewed through that same lens.

If Roger Federer or Serena Williams decide to serve underhand, the lens would change. Both Federer and Williams have amassed so much credit over their respective years of dominating the sport, that their reputations are bulletproof. Do you still remember the SABR?

Contrast the crowd’s reaction to Federer’s unconventional tactic to the reaction Kyrgios got when hitting the underhand serve. Admittedly, it is not an apples to apples comparison. In the SABR, Federer is trying to get Djokovic out of his rhythm, sure. Yet he still puts himself at a bit of a disadvantage by decreasing the time he has to react to Djokovic’s serve by returning so close to the service line. In other words, during the SABR, you react. During the underhand serve, you are completely in control of the shot. Regardless of that particular difference between the SABR and the underhand serve, just listen to the different reactions of the commentators and the crowd. What would the reaction be if Federer served underhand to Nadal at this year’s Wimbledon? You tell me.

Genuine Tactic

There is one more subtle difference between the two tactics, and that is the timing of their deployment in the videos above. Notice the score when Kyrgios serves underhand to Nadal: 2-5, 40:0. Serving at 40:0 on grass, Kyrgios is an overwhelming favorite to win the game. Even if he loses the point, at 40:15 he is still well ahead in the game. By the same token, once he wins the point, Nadal is clearly favored to win the set when serving at 5-3. In a way, that 2-5 40:0 point is largely irrelevant to the outcome of the first set.

Contrast that with the timing of Federer’s SABRs in the video above. First one at 1-1 15:30, and the other up 3:1 in the tiebreak. Both are tremendously important points. If Federer goes up to 15:40 in the third game, he has a good chance of going up a break in the match. Similarly, to go up 4:1 in the tiebreak, and serving, puts Federer well on his way to securing the first set 7:6.

Looking at their respective strategies from this angle, it really does seem like Federer’s SABR was a legitimate tactic deployed to surprise Djokovic and gain an advantage in the match. Kyrgios’ underhand serve was used in a situation that really didn’t matter.

I think that if the underhand second serve is used as a real, genuine tactic, some of the players’ and fans aversion would be muted. What is a “genuine tactic?” That is hard to pinpoint, but some things to look out for would be:

  • Used early in the match to force the opponent to adjust
  • Used throughout the match if the opponent doesn’t adjust; for example, using the underhand serve twice a game instead of twice a set
  • Used on important points
  • Used in multiple matches against a variety of opponents

Returner is Not a Victim

This last point falls more on the fans and members of the media rather than the players themselves. And that is simply to recognize that the returner can adjust their position, if they don’t like being served to underhanded. Just like if Djokovic didn’t like Federer’s SABRs, he could hit his second serve a little harder, and aim it at the body of Federer. Once Federer sees that his strategy is not having the desired effect, he’ll stop doing it. If I don’t like somebody slicing backhands, I can hit through their forehand. Tennis is a game of adjustments, and allowing that one’s return position is a variable that the opponent might want to exploit would go a long way towards freeing up some players to hit more underhand serves without fearing the crowd’s reaction.

There are plenty of examples of tactics evolving in various sports around the world. In basketball, once the sport has recognized and embraced the value of the three point shot, the game has evolved into a wide-open, pace and space sprint, as opposed to the slow slog of yesteryear when games were dominated by battles in the post. In American football, the multiple wide receiver formations are much more prevalent in today’s era of the pass than the run-heavy, multiple tight end sets of the years past. In baseball, you might see the shortstop lineup anywhere on the infield on defense these days, depending on who the batter is. Seeing a little more of the underhand serve would be a welcome sight for yours truly; a wrinkle, and a new tactical element in a game that has recently been a little lacking in variety for my taste.

1 Comment

  1. Andrew Cueva says:

    insightful post. It’s funny nobody begrudges a drop shot hit during a rally when the opponent is 15 feet behind the baseline…that’s considered a smart tactic. For all of Krygios’s poor mastery of strategy, he is an exemplary tactician. Besides throwing in an underhand serve, he will also fire a 135mph second serve. That’s tactically brilliant. If he deployed the tactics at more strategically critical points in his matches it would have more of an impact on the outcomes.


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