Hopefully burrow off the bench but think he will start

How do you "mark" a dummy half out of the game, other than by winning the collision and slowing the play the ball?

If the markers are disorganised because the ball carrier has won the collision, there's naff all you can do to stop the dummy half wreaking havoc.

Fair enough. Whatever the technique that's the key: stop Roby from DH.

Well of course you have to try and win the collision and be technically smart in the tackle but you can also have a plan in mind to provide cover for the marker tacklers with tight defence around the ruck with Roby as a target. When we last played them we were very sloppy around the PTB area with a lot of missed tackles. I feel sure the coaches will have replayed the VT on that match a few times.

Should be a good game!

We could always attack Roby in attack making him complete more tackles try to drain his energy a little.