Kieran Tierney coming off against Dundee has left Celtic dealing with strict concussion protocols. A head knock brings clear rules, and those rules mean the next few games may come too soon for Tierney.

The one certainty is Livingston on Wednesday night. Tierney will not play. Concussion protocols mean a set rest period, and that does not end in time. Even if he feels fine, he cannot be involved. That decision is already made.

Under concussion protocols, a player must complete a minimum return-to-play period that usually lasts around six days at the earliest. That includes full rest at first, then light training, before contact is allowed again, with medical checks at each stage.

If any symptoms return, the process resets and can stretch into a second week. That is why timelines are never exact and why clubs tend to be cautious.

Next Sunday at Rugby Park is where things become less clear. By then, the required days will have passed. In theory, Tierney could be available. It depends on how he feels, how he reacts in training, and whether he can handle contact without any issues. That is what will decide it.

Rugby Park is not a gentle place to return. The pitch is demanding, the tackles come early, and the game can turn scrappy fast. Celtic also have Stuttgart just days later in the Europa League, which changes how much risk makes sense.

That European game could change the thinking. If there is any doubt at all, waiting makes more sense. Stuttgart will be intense, but it may be a better return to see if he is ready.

Celtic have cover at left-back, which helps. There is no need to hurry a player who has already dealt with setbacks.

However, with Marcelo Saracchi making his long-awaited return to replace Tierney, there are also questions over whether Saracchi would be able to play 90 minutes on Wednesday, meaning Liam Scales or Anthony Ralston may offer cover for Saracchi, as they have done at times this season.

So the picture is simple. Livingston is ruled out. Kilmarnock is possible. Stuttgart feels more likely. The answer will come over the next week with Tierney set to be closely monitored.