Sharpen passing and scanning under continuous time pressure. Because a second ball is always approaching, players have to know where their next pass goes before the current one reaches them.
Set three mannequins in a line down the middle of a 16x10m box with a station either side. Eight players take a station each on a fixed circuit that alternates through the spine and along the outside. Run one ball until the order is automatic, then introduce the second ball half a lap behind. Play two touch. If the balls close on each other, the group has lost the rhythm: stop, reset the gap, and start again rather than letting them collide.
A single ball on a fixed circuit teaches an order. Players learn that they receive from one player and pass to another, and after a few minutes they can do it without looking, which feels like success and is actually the problem. Once the pattern is automatic there is nothing left to solve.
The second ball puts the problem back. It enters half a lap behind, which means that from the moment it joins, every player has a ball arriving roughly every four passes rather than every eight. There is no longer a gap in which to watch your own pass travel, admire it, and then look up. The head has to come up between receiving and passing, every time, because the next ball is already on its way round.
The mannequin spine matters more than it looks. Half the passes in the circuit go through it, which means the first touch cannot simply stop the ball: it has to move it across the body to open the line. A player who takes a settling touch straight in front of him has a mannequin between him and his target and needs a second touch to solve it, and the second touch is exactly the one the drill has removed the time for.
The honest test of whether it is working is the gap. If the two balls stay roughly opposite each other for a full minute, the group is passing at the tempo of the circuit. If they close on one another, someone is rushing their pass rather than raising their head, and the fix is not to go faster.
Save it to your private drills, then change the animation, adjust positions, swap equipment, or drop it into a session block. Or start from a blank pitch and build your own.