What “Under 18.5 Games” Means in Tennis Betting
In Over/Under tennis betting, you predict the total number of games played in a match.
- Under 18.5 games means you’re betting that the total number of games in the entire match will be 18 or fewer.
- If the match reaches 19 or more games, your bet loses.
This market is usually for best-of-three sets matches (like ATP, WTA, or Challenger matches).
Example Match Scenario
Let’s use Carlos Alcaraz vs. Daniil Medvedev as an example.
Example 1: Under 18.5 (Bet WINS)
Final score: Alcaraz wins 6–2, 6–3
Total games = 6+2+6+3 = 17 games
Under 18.5 WINS
(because total games = 17, which is less than 18.5)
Example 2: Under 18.5
(Bet LOSES)
Final score: Alcaraz wins 6–4, 6–3
Total games = 6+4+6+3 = 19 games
Under 18.5 LOSES
(because total games = 19, which is more than 18.5)
When to Bet Under 18.5
You should consider betting Under 18.5 games when you expect a one-sided match — typically where a strong favorite dominates a weaker opponent.
Ideal Situations
- Big skill gap: Example – Novak Djokovic vs. qualifier.
- Djokovic often wins in straight sets like 6–2, 6–3 (≈17 games).
- Fast surfaces (grass, indoor hard):
- Favors aggressive players who end points quickly (few long games or sets).
- Dominant server + weak returner:
- Example: Hubert Hurkacz vs. clay-court player on hard court. Hurkacz could win 6–3, 6–2.
- Inconsistent player vs. in-form favorite:
- When one player is low on confidence and likely to lose badly.
When to Avoid Under 18.5
Avoid betting Under 18.5 when:
- Both players are strong servers (tie-breaks likely → longer sets).
- The underdog is solid and can hold serve often.
- It’s a clay-court match, where breaks are common and sets often go 6–4 or longer.
Betting Example
Match: Iga Świątek vs. Camila Giorgi
Surface: Clay
Świątek is dominant and regularly beats lower-ranked players quickly.
- Predicted result: 6–2, 6–3 → 17 games
- Under 18.5 is a smart bet
Expert Betting Tips
- Check recent form: Look for players who have recently won matches in straight sets with low total games.
- e.g. Świątek often wins 6–1, 6–2.
- Use live stats: If the favorite is breaking serve easily and winning fast, Under 18.5 (live in-play) can be profitable.
- Avoid tight matchups: When two players are close in ranking, totals usually go over 18.5.
- Watch for early-round mismatches: Under 18.5 often hits in Round 1 or 2 of tournaments when top seeds face qualifiers or wildcards.
Summary Table
| Scenario | Total Games | Bet Result |
|---|---|---|
| 6–1, 6–3 | 16 | Under wins |
| 6–2, 6–2 | 16 | Under wins |
| 6–3, 6–4 | 19 | Under loses |
| 7–5, 6–3 | 21 | Under loses |
| 6–0, 6–2 | 14 | Under wins |
Would you like me to create a comparison guide showing when to bet Under 18.5 vs. Over 18.5 (with sample matches and reasoning)? It helps you instantly spot the right bet type.