Simon knows all about what lies ahead for Don, recovering from his cruciate operation in Canada just over two weeks ago, and has been working closely alongside John Green with him to ensure the foundations are set for as quick a recovery as possible.
Nonetheless, 'quick' in this case means six months or so, and Simon, whose career at West Ham was ended by injury after an accidental collision in training with Julian Dicks, says: "The one problem he will have is mentally. It is easy to become disheartened and depressed at times - especially when you can't see any change in how you are progressing.
"At certain times along the rehab period you come to a plateau where you work hard to move on to the next level and you don't seem to progress. It is times like that when you need the support of the people around you - and I think the medical support here is very good, so hopefully he shouldn't suffer those problems."
As for the physical side of things, Simon says: "I think he is progressing very well. Obviously it is the initial stages and it is important to get that right.
"We have been looking to get the inflammation and swelling down on his leg and for him to regain his mobility as soon as possible, especially regarding his leg and the full extension and bend of it, and he is working very hard at it.
"He realises he has got a long hard road ahead of him and hopefully he will progress well all the way through that.
"I think with the operation he has had the success rate is very high and we know that people have come back from worse cruciate injuries than that. The battle ahead of him is one he should rise to - and there is no doubt that he will come back from it."