Underarm serve

The underarm serve is struck below shoulder level (In Wikipedia. Retrieved July 19, 2019, from https://en.wikipedia.org/wiki/Serve_(tennis)). Normally, tennis players choose overhead serve. However, they occasionally choose underarm serve. I am curious about when underarm serve occurs. It is a controversial whether the underarm serve is rude for opponent. Some people consider the underarm serve is effective under certain situations (https://www.quora.com/Is-underarm-serve-disrespectful-and-why).

Strategic advantage

To my knowledge, no study has examined what is underarm serve’s advantage and disadvantage. In my opinion, there are 2 advantages.

1. Ace
When the server can hit very fast serve, the returner sometimes move back a bit to set aside sufficient time for return. The server hit a short serve to acquire an ace.
2. Move the opponent and create open space
Even the opponent returns for short serve, there are open spaces. The server can hit passing or lob shot for open spaces.

Strategic disadvantage

1.Counterattacked
The server has risk of being counterattacked if the serve is not short and low bounce enough to take advantage in incoming rally or the receiver anticipates the underarm serve.

Data analysis

Data sources
The data includes the matches of male professional tournaments. I acquired the positions of the players and the ball landing positions by a two-dimensional direct linear transformation method. I excluded fault serves. All serves were made in advantage side.

Visualizing player and ball positions
Figure 1-5 show the positions of players and ball. The red and white squares show the positions of the server and the receiver, respectively. The green circle shows the ball positions. The numbers in marker symbols show the sequences of the hitting or the bounce. The average of the hitting position for the returners was 3.82m behind from the base line.

Ace
Figure 1-3 shows the servers acquire the points by short serves.

Create open space
Figure 4 shows the server moves the opponent and creates open space. The server hit passing shot.

Counterattacked
However, underarm serve doesn’t always work. Figure 5 shows the opponent returns the serve to the corner and then hit drop volley. The server is counterattacked under situations like this.

Limitations

The data in this post were case example. The sample size of the data was limited. This is because underarm serve is rare. In this post, I did not compare the positions between overhead and underarm serves.

Epilogue

I visualized the positions of players and ball related to underarm serve. Underarm serve may be effective under particular situations.
See you next time!