TOKYO, 9 Oct - The restart is more than just the act of kicking the ball back to the opposition after they have scored points. Today it is the third set piece, after the scrum and the lineout, an opportunity to gain an advantage over an opponent who may not have spent much time focusing on how you kick off.
If you kick the ball short, you are looking to win it back. If you do not win it back, you give the opposition the ball close to your line. In the example below, Fiji's Ben Volavola kicks the ball high so that it hangs in the air, giving second-row Leone Nakarawa time to get underneath it and win it back for Fiji.
This type of kick-off is common in rugby sevens, a discipline in which Nakarawa won a gold medal at the Rio 2016 Olympic Games.
Some teams will use the kick-off to tactically remove an opposition player from the next few phases of play, in this case, South Africa's Willie le Roux. By targeting Le Roux, New Zealand are nullifying one of the Springboks' strongest assets: Le Roux's left foot.
His ability to kick the ball as far downfield as possible makes Le Roux a key ingredient in South Africa's 'exit strategy'; if the Boks are under pressure in their own 22, he can be relied upon to send it back into the opposition's half.
By kicking the restart at Le Roux and tackling him to set up the first breakdown, it takes him out of the next phase of play. In this case, Faf de Klerk is left to kick instead and the All Blacks win the ball back barely 10 metres up the pitch.
The kick-off battle of wits doesn't go just one way. The receiving team have no say over where the ball is kicked but they can decide how to position their own players so they regain the advantage.
In the example below, Wales line up with four pairs of players ready to receive the short kick and the remaining seven players stood deep. You might think that they have narrowed their options and could cover much more space as 15 individuals, but Wales do this so that in the case of a short kick-off, one member of the pair can lift the other to catch the ball.
Liam Williams, for example, is stood with flanker Aaron Wainwright, with Wainwright ready to lift his partner if the ball is kicked towards them. With Williams absent from his full-back position, back-row Josh Navidi steps back. You can spot him on the left wing, deep in the Wales 22, ready to charge back at the Australians if they send the ball down there.
With this set-up, Wales believe they have the advantage no matter where the ball is kicked.
Next time you watch a team kick off, try and work out whether they are trying to win the ball back or not. If they do not attempt to win the ball back, what are they doing? Are they just kicking really long? Are they targeting the strongest player to contain him? Can you find a weakness in a team's kick-off strategy?