"We have been doing a lot more physical work and I can tell you that having a 6ft 4in man mountain crash in to you - as we have been doing - is no fun!
"But it's all part of assessing Jason's progress and like I say he is moving forward. He is back training, in some capacity, with the first-team now and the signs are encouraging."
Meanwhile Town boss Joe Royle is hopeful that De Vos will be back for the Sheffield United game a week on Saturday: "The international break has helped us with Jason's injury and while we hope he is okay for the Sheffield game, we will be guided by the specialists because rib injuries are particularly difficult."