The centre started in the Calcutta Cup win over England on the opening weekend of the Six Nations but then found himself surplus to requirements for the defeats by Wales and France.
Johnson was replaced at 12 by Warriors team-mate Sione Tuipulotu and never even made the bench for either game.
For the third game in a row Johnson is back on club duties and will be in Wales this weekend as Glasgow seek to maintain the form that has seen them win five on the bounce in the United Rugby Championship.
It’s tough on a player who has been a mainstay of the national side for the last couple of years, striking up an effective partnership with Chris Harris. But Scotland’s loss can be Glasgow’s gain and Wilson is delighted to have Johnson available.
“There is a fair bit of competition there, which is what we want in Scotland and Glasgow,” said the Warriors coach, who believes Johnson can play his way back into the Scotland reckoning.
“Sam is an outstanding rugby player. He played against England in the first win, though hasn't played the last two. But I think he still has a huge amount to offer. Along with Sione that is great competition there so we will see how that pans out.
“I think he now has a good chance to go out there against good opposition and really put his hand up. Then I think he genuinely has a chance to be considered for selection.”
Glasgow have had to contend with a number of injuries and there are seven changes to the side which saw off Benetton last month.
Matt Fagerson, who suffered a blow to his foot in Scotland’s loss to France, remains sidelined but is making “good progress” according to Wilson. Whether he will be fit for selection to face Italy on March 12 remains to be seen.
Jamie Bhatti and Rufus McLean, who were both part of Scotland’s original Six Nations squad, are both injured. Bhatti is recovering from a broken thumb while McLean has a minor groin problem. Scrum-half George Horne is also missing and could be out for some time.
“George is going to have a medium-term lay-off with a knee injury,” said Wilson. “It’s a bit of a blow for George, because he was getting some game time and playing well, but unfortunately the knee injury from the Benetton game is a bit worse than we’d hoped.”
Jamie Dobie will come in for Horne against Scarlets and will be partnered at half-back by Duncan Weir who returns in place of Domingo Miotti who has dropped out.
Josh McKay returns from injury and replaces McLean on the right wing, with Ollie Smith retaining the full-back’s jersey. Cole Forbes plays on the other wing in place of Walter Fifita.
There are three changes in the pack, with Johnny Matthews in at hooker ahead of Fraser Brown, Rob Harley taking over from Richie Gray at lock and Ally Miller picked at openside flanker in place of Tom Gordon. Brown, Gray and Gordon are on the bench.