Who will make the next double fault?
It takes a lot of observation and, of course, a little luck with your timing when you want to successfully bet on the next double fault. But then, the odds are very good, considering that on average, player do not hit too many double faults during a match. With a little understanding of the game and the techniques, you can dramatically increase your chances of getting it right.
This is not something many sportsbooks offer as an option to bet on, but Intertops (open for US clients) does. I suggest you check them out, they are a great choice for tennis betting. To go to their website, just click here.
Service basics
As you know, players get two serves for each point (unless the ball touches the net and lands inside the service box). Players use their first serve for a strong shot, with little or no ball rotation, in order to put maximum pressure on the opponent or win the point outright.
The second serve is where it gets interesting for this kind of bet. For this shot, players aim to have the ball pass the net with some safety distance (i.e. higher over the net). Normally, that would mean the ball has to be slower in order to land inside the box. Now that would be too easy for the opponent, which is why a good tennis player hits the second serve with the same speed of movement or almost the same speed he uses for a straight first serve, but a big part of that speed will be put into ball rotation. In order for a fast ball to pass high over the net and into the service box, you need mostly forward rotation of the ball (topspin), although sidespin (slice) or a combination of topspin and slice is very effective as well.
This kind of technique allows the ball to pass the net with some vertical "security distance", and when the ball bounces, the rotational energy will be released and transformes to a faster, higher ball bounce. This ball bounce gives the shot depth and makes it difficult to return. Very often, ball rotation is also used to give the ball a trajectory towards the outside of the court, or bounce closer than expected towards the other player's body.
Increases probability of double fault due to technical "tells"
In order to give spin to the ball, the players must allow for their arm and wrist to be "loose" - without this, the necessary speed of the racket will not be achieved, and without speed, they will not generate enough spin. So, if you see that a player is a little too tight, there is a good chance that a double fault will follow.
Another thing to focus your observation on is the throwing of the ball. In general, for a second serve the ball should not be thrown too much forward , in order for the hitting movement to be more from the downside up, instead of the more back-to-front movement of a first serve. When a player throws the ball forward and past the baseline, then the shot will usually be lower that what is required for a safe 2nd serve - which increases the possibility of a double fault.
Increased probability of double fault due to match situations
When the stats show that a player is winning significantly less points when serving 2nd serves, he may feel the need to give more power to his 2nd serve - that would obviously lead to a higher risk and more double faults.
When a serving player is under a lot of pressure, like a score where he has a break point against his serve, the chance of a double fault increases a lot. Remember, this kind of threat makes players tighten up in more than one way, and that is very bad during the execution of both first and second serve.
Last but not least, some players have a strong tendency to commit more double faults when serving from the right side or from the left side. Those two positions require small adaptation of stance and technique, and because of that many players have a stronger and weaker side. Watch them for a while, and you will be able to see which side is stronger!