Diskin, 32, will miss around a month with a torn calf muscle, while Sidlow could be back within three weeks despite initial fears he had suffered a broken leg.
Scans have shown he has suffered ruptured ankle ligaments, but coach Francis Cummins is remaining positive.
He said: “This is great news for us, given the initial prognosis.
“Both injuries are as good as they could possibly be, I guess, meaning we should have Matt and Adam back fit fairly soon.
“These sorts of injuries are often hard to judge, but I am confident of speedy returns for them as they are in great shape otherwise.
“They are in the brilliant hands of our medical team and I wish them well in their respective recoveries.”