The tachi-ai (立合い) is the initial charge between two sumo wrestlers at the beginning of a bout.

There are several common techniques that wrestlers use at the tachi-ai, with the aim of getting a decisive advantage in the bout:

• Charge head-first
  • Usually to attempt to use one's weight and momentum to force the opponent backwards out of the ring. Such a headlong charge in a low position can lead a more agile opponent to dodge out of the way and slap the charger on the back to push him to his knees.
• Try to raise the opponent up into a vertical position
  • Makes the opponent more vunerable to being pushed backwards toward the ring edge and also to certain types of throw and pull down moves.
• Thrust the opponent's chest
  • Again force the opponent backwards towards the ringedge, or to unbalance him sufficiently to execute a beltless arm throw or a pull down move. Powerful thrusts can on occasion be enough to force the opponent to fall over in the ring.
• Slap the opponent's face
  • Shock the opponent into lowering his guard to gain an advantageous position, in certain cases the slap has been known to be enough to stun an opponent into falling to his knees. This move is forbidden in amateur sumo.
• Grab the opponent's belt
  • Use the belt to gain leverage to force an opponent backwards, or to execture a belt throw
• React to the opponent's move
  • Includes dodging out of the way of a incautious charge as described above, or dodging the attempted slap and using the opponents lack of balance to gain an advantageous position.
• Surprise the opponent
  • Includes such moves as clapping one hands in front of the opponent's face and using the momentary blink to duck underneat to get a strong belt or leg grip to try to subsequently throw the opponent.