McCallum, who is on loan from West Ham, limped out of the 2-0 defeat due to a persistent foot injury. The striker has what is known as a bursa – a small lump filled with fluid – on his heel and the pain of it rubbing against his boot was too much for him to continue.
But Locke said: “Paul was back training [on Tuesday] morning. He has a bit of a problem with his heel but we have managed to sort that out in the last 48 hours. As long is there is no reaction then he should be fine for the weekend.”
Holt suffered an adverse reaction in his comeback match after three months out with a fractured metatarsal, but Locke is hopeful he could return to training tomorrow or Friday.
He told Hearts TV: “Jason’s had a little setback but, hopefully, it’s nothing too serious to worry about.”