Justin Marshall's chalkboard: How Wales can cause AB's problems

All Black Malakai Fekitoa looks on during a New Zealand All Blacks training session at Eden Park on June 9, 2016 in Auckland, New Zealand. Photo / Getty Images.

There has been a lot of talk during the week about Wales' chances in this test and in particular the area they are going to attack against the All Blacks.

A lot of the speculation has been about the possible focus on Ryan Crotty and Malakai Fekitoa because they haven't played a lot together, and that has been mooted as a possible weakness for the All Blacks.

Firstly, I suspect Wales would have gone to their midfield of Jamie Roberts and Jonathan Davies anyway because they usually do. With big wing George North also able to operate in that area for Wales - and all three have played for the British and Irish Lions - it doesn't take a rocket scientist to suggest that is an area of strength for them.

From a New Zealand perspective, yes there is a slight combination issue in the midfield because this is only the second time Crotty and Fekitoa have started a test together (the first was against Scotland at Murrayfield in 2014). But, if you boil it down, both are excellent tacklers. They are strong and offensive defenders, so it doesn't matter who runs down that channel, those two guys will knock them over.

All of which brings me to my main point - Wales can't just shovel the ball to the midfield and expect to wreak havoc.

Their focus has to be halfback Rhys Webb and first-five Dan Biggar. All the talk of midfield weaknesses will make the All Blacks prickly and they will gravitate there. But they can't go there straight away if they are being pulled inside by Wales' No9 and No10.

In the first diagram, I have shown Webb and Biggar passing the ball without engaging the defence, which puts pressure on Roberts and Davies.

In diagram two, you see the inside work of Webb, who has perhaps taken a step with the ball, holding the inside defence. Biggar, holding ball in two hands, manipulates the defence and puts Roberts or Davies into a gap which makes those players twice as dangerous.

In my opinion the attacking qualities of Webb and Biggar are more important for Wales than those of Roberts and Davies because they have the potential to give their teammates the time and space they desperately need.