This might look like a simple 6v3 rondo, however it has been used elite coaches such as Antonio Conte to deliver the defensive principles that they want to imprint in their back three. The session is specific to a back three but could be adapted to a back four if that is what is required.
The session see’s the reds look to keep possession and play through the rondo, the yellows look to apply pressure and win possession back. However, more importantly the yellows must make sure they don’t get split by the reds. So they look to travel as a unit, limiting the space between them making it difficult for the reds to play through the central area in the practice. This is explained in more detail on the next page. 

DON’T GET SPLIT

One of the greatest challenges when playing as a back three, is to limit the space between the three defenders, ensuring the opponent isn’t able to play between the spaces left. When the reds are in possession it is important that each defender has a different role. The first defender applies the pressure and plays in the most advanced role, whilst the second and third defenders offer cover and balance in a narrow position that forces the opponent to play around the defensive shape.
As possession moves from left to right, it is important that the back three is able to adjust and make movements to counteract their actions. In the example shown above, it would be expected to see the right sided centre back travel with the ball to apply passive pressure to the player in possession, whilst the other two defenders drop behind the first defender and offer the cover and balance that was previously mentioned.  This is the most important a coach can share with their players when taking part in this practice.

Avoid the split, encourage the players to prevent the attackers playing passes between their defensive lines, this should be seen as an aim. 

Use players who are likely to play together and will benefit from working together and practicing the distances and angles