Physio Simon Webster says: "He had a calf knock, a haemotoma which took longer than we expected, but hopefully he will be back in training next week."
As for the other injuries, Simon says: "Don Hutchison is in his seventh week of rehab and is progressing nicely, but it is of course slow progress.
"Gary Charles has started running again after a lateral meniscus problem and having some cartilage removed.
"Paolo Di Canio is another one who will be okay for pre-season, and is continuing his treatment in Bologna.
"Sebastien Schemmel is doing absolutely fine and is off crutches - there was no fracture, it was more soft tissue, and he is having early treatment.
"Louis Riddle, who has had an ankle problem, is pushing on and we are having to hold him back."
Simon has also paid tribute to Izzie Iriekpen, who has beaten the odds to overcome a knee injury - and forced his way onto the bench at Newcastle on Saturday for the first time in two seasons.
"He has put in a lot of hard work," says Simon, "and we have tried various ways of working and resting him.
"With the more football specific work he has come on in leaps and bounds and, where at one stage it didn't look too good, he has improved greatly now.
"I am pleased for him, because he is just a young lad starting out."
He is also delighted that Ian Pearce, who has had a similar length of time out, has returned, and adds: "He has done fantastically well, and after a hard start to the campaign, he has played his part in our late season success."