SWITCHING PLAY IN DEFENCE (progression)
To move on from the last practice, another set of defenders can be brought in to face the current 4 players involved in the exercise i.e. in diagram 4 x (A), 4 x (B); no other players on a full sized pitch except server (S).
Diagram (1)
In this practice (A3) receives the ball from a server (S) who starts in the central area

(A3) transfers the ball (first time when possible to (A4), who moves forward slightly before transferring the ball to (B1) - the opposing flank defender

NB As (A4) is progressing, (B1) will tend to back away and this will mean (B2), (B3) and (B4) readjusting their positions as well e.g. (B2) may consider a position where he can cover (B1) or simply retreat slightly in the central area. The other two will react accordingly, much depends on the speed of (A4)'s control, move and pass to (B1)

On receiving the ball (B1) transfers it to (B2) who then can either play it on to (B3) or pass directly to the opposite wing to (B4) who is moving forward

Once (B4) receives and controls the ball he plays it back across to (A1) OR (A2) to begin again in the (A's) defence line.
POINTS TO NOTE
(1) Players on both lines must keep their distance from each other and their shape/balance in defence
(2) Pass quickly (first time when possible) switching the passing in defence - not always a pass to the next nearest defender
(3) Be aware of positional play, moving around to support and cover, particularly those passing or receiving the ball. Retain a width and depth in defence, even when in possession i.e. players taking positions off other team mates
(4) Work on quality of passing, accuracy and correct weight on the pass
(5) React defensively to the movement of the ball on the other side. Positional play is crucial e.g. as (B1) plays to (B2), the (A) line defence should be preparing for eventualities. So should (B2) play a long diagonal pass to (B4), then (A1) will be positioned favourably, while (A2) will have moved as cover to (A1).