Johnston has only played a couple of practice games since the summer after being transfer-listed by Reid when he refused to sign a new contract. He has also been training with the reserves while the dispute has continued.
However, he could make his first competitive start of the season on Saturday when Scotland face Bosnia in their European Championship qualifier in Sarajevo. The match is the first part of a double header, with Craig Brown's side due to face Estonia in Tallinn the following Wednesday.
It has been a frustrating time for Johnston, who has scored in his last two appearances for Scotland, against the Czech Republic and the Faroe Islands. But he now feels there might be a breakthrough at the Stadium of Light and he is due to meet Reid with his agent, possibly at the end of next week.
"Before I left to go to Scotland the manager said he would speak to me when I got back," he said. "Despite all that has happened in the past couple months I don't have a problem with Peter Reid. I need to get everything right about a new deal but I don't won't to dwell on it too much. The manager gave a good report to Craig Brown and it's a great boost to be called up by my country."
Brown admits it is a gamble calling up Johnston but has indicated he will start against Bosnia. "There are others who are in the same boat and have not had much match practice," Brown said. "You look at Colin Hendry, Craig Burley, John Collins and Christian Dailly. But they are all in contention.
"I wouldn't have chosen Johnston in the squad if I hadn't spoken to Peter Reid. Typically he was spitting and swearing about the contract but he wasn't holding it against him. He told me Johnston had been playing in closed-doors games and was flying."
As Hendry and Dailly have both had injury problems recently, Brown will almost certainly decide against using them as a central defensive partnership. Hendry, however, may resume the captaincy as Tom Boyd is injured while Dailly could replace Callum Davidson on the left flank as his Blackburn team-mate is suspended.
Meanwhile, the Tartan Army have been warned not to have a kick-about on waste land in Sarajevo as they risk being blown up. Landmines from the civil war still litter the Bosnian capital.
n Bosnia's injured Real Madrid forward Elvir Baljic will miss Saturday's game with a knee injury.