Reading serve habits: when a return prediction helps—and when it costs

An opponent’s preference for one serve direction can be useful information. Using it, however, is different from running to one side before the ball arrives. A returner can give the likely direction a small advantage in preparation while retaining room to respond to the actual ball. The benefit on frequent serves and the cost on rare ones belong in the same assessment.

A University of Bern study published in 2026 examined this distinction through movement. Players learned that virtual serves favoured one side. Performance improved for the frequent direction and declined for the uncommon direction, while the overall result improved. One wrong-footed return therefore tells only part of the story; a few correct predictions do not settle the next serve either.

What the experiment separated

Fourteen right-handed male competitive players returned virtual serves in an extended-reality environment using a physical racket. They were not a sample of fourteen touring professionals. Direction probabilities began at 50:50, then became 80:20 without an announcement of the change. The serving avatar used the same motion every time, removing directional clues from its movement.

That design separated information learned from earlier serves from information in the current ball’s flight. A live opponent offers additional clues and variations in motion, speed and spin. The experiment isolates one contribution to preparation: how a pattern of locations can influence the returner before the present ball has revealed its destination.

The study also separated two outcomes: starting movement in the correct direction and making racket contact with the ball. A player can choose the right side but arrive late or miss the contact point. Putting the return inside the court, then winning a rally, adds further tasks. The figures below describe direction and contact, rather than point-winning percentages.

Scene one: equal probabilities left two options open

Under equal probabilities, the average weight shift did not favour one direction in advance. Neutral preparation is different from doing nothing. A player can make a preparatory movement and gather information without giving one side an early preference. Delaying all preparation and preserving both directional options are separate choices.

A club player facing a new opponent has limited evidence at first. Two serves to the backhand provide a starting observation, but not necessarily a habit across every score and court side. Combining deuce and ad returns, or first and second serves, can merge different decisions into an apparently simple preference. Narrowing the context makes the observation more useful.

For example, repeated second serves toward the backhand in the ad court present a different problem from powerful first serves in the deuce court. This is a way of organising observations, not a claim about a particular opponent. Describing the circumstances is more flexible than labelling someone a player who always serves to one wing. When the circumstances change, the expectation can change with them.

Scene two: a common direction influenced preparation

After exposure to the biased distribution, a small weight bias toward the frequent side was evident before the serve. The measure concerned the body’s centre relative to the ankles; it was not evidence of a large sideways step taken in advance. Two returners can look similarly ready while creating slightly different starting conditions for their next movement.

This makes prediction and reaction less of an either-or choice. Experience can influence preparation while the ball’s flight continues to update the decision. The useful concept is an initial preference that remains open to new information, rather than a fixed answer followed by automatic execution. Prediction can shape the body without requiring an obvious early lunge.

That concept is not a prescription to copy a particular amount of lean. Starting position, movement capacity and serve speed change the cost of reversing direction. The practical comparison is whether the adjustment creates more room at contact or requires a hurried stop and correction. Feeling as though you anticipated well matters less than being able to play the ball that actually arrived.

The last two rows describe different serves within the biased condition, not different groups of players. Improvement on the frequent side and difficulty on the rare side must be considered together. In the experiment the distribution was imposed. A real server can notice the returner’s adjustment and change direction, so a useful pattern can also lose its relevance.

Scene three: the uncommon ball exposed the cost

Reduced performance on rare-direction serves shows the price of favouring the more likely option. These errors can be memorable: an obvious hesitation toward the wrong side attracts more attention than several slightly more comfortable contacts. Judging preparation by the most awkward point alone can hide where the same choice helped.

The opposite mistake is treating two good returns on the preferred side as proof that the adjustment should always stay. Can the player still respond when the server changes course? Did a well-prepared contact lead to an overambitious miss? Separating the value of the expectation from the execution of the stroke prevents a movement problem and a shot-selection problem from becoming one vague failure.

Imagine a practice sequence with eight balls to one side and two to the other. Counting only the common balls removes the rare-side cost; remembering only the two difficult balls removes the benefit. This hypothetical sequence illustrates the distribution rather than prescribing a match strategy. Whatever mix is used, results from both directions are needed to evaluate the whole choice.

Good movement still leaves time for information

A 2019 study by Mecheri and colleagues observed world-class adult and junior men and women returning real serves. Its institutional abstract reports that the four groups began the split step around server contact and landed when early ball-flight information was available. Current information still has a role even when an expectation influences preparation.

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Earlier movement is therefore an incomplete definition of a better return. The player needs usable information and the ability to act on it. Conversely, waiting for complete certainty before preparing the body can leave too little movement time. The task is to coordinate preparation and information, rather than compete to make the first visible step.

The 2026 protocol placed the equal-probability blocks before the biased blocks. Later performance therefore also occurred after more practice. Its design supports examining the difference between frequent and rare directions and the accompanying weight shifts; the before-and-after totals should not become a promise that learning an opponent’s habit will produce a fixed improvement in a match.

Practice a decision that can still change

Two players who can control serve direction can separate a known-direction phase from an unknown-direction phase. Begin at a manageable pace, mix the sides, then introduce a tendency known only to the server. The returner should play the ball rather than merely call a prediction. This is a suggested club exercise informed by the research, not a replication with a guaranteed training effect.

Assess the stages separately: did the player begin in the right direction, contact the ball, and return it inside the court? An initial directional error raises a different question from a late contact after a correct choice. Repeated misses after contact bring the target and swing into consideration. A single success-or-failure mark conceals which part needs work.

For a player still learning the basic movement, USTA Florida’s split-step and ready-position lesson provides an introduction. Linking preparation and contact at a comfortable pace comes before complicated probability patterns. If the server cannot yet control placement, first establish a repeatable feed rather than treating an accidental cluster of balls as a deliberate tendency.

In the next return session, retain the other possibility even after noticing a pattern. Compare the extra room gained when the expected ball arrives with the ability to change the decision when it does not. The aim is to meet the real ball in a better position, rather than win a guessing game about where it will go.