Kieran Tierney was missing from Celtic training on Friday as concern grows over the defender’s fitness ahead of the weekend clash with Rangers.

The left-back was forced off during Celtic’s win over Aberdeen earlier in the week after taking a knock to his foot. Tierney had already opened the scoring at Pittodrie before the injury disrupted his night and eventually brought an early end to his involvement in the match.

Since then, attention has turned to whether he will be fit for Sunday. The Scottish Sun reports that Tierney missed training on Friday.

Celtic face Rangers in a Scottish Cup quarter-final, and Tierney’s absence would leave a gap on the left side of the defence. The Scotland international has been a regular outlet when Celtic build attacks down that flank, often pushing high to deliver crosses or support the winger ahead of him.

His ability to drive forward from deep has been a feature of Celtic’s play this season. Against Aberdeen he was again heavily involved, arriving inside the box to score from close range after a corner created the opening.

If Tierney cannot recover in time, Martin O’Neill may need to adjust the back line. Marcelo Saracchi is the most obvious replacement and has already stepped in at different points during the campaign.

Celtic supporters are now waiting for clarity from the manager. O’Neill is expected to speak to the media later on Friday, where he will likely address the situation.

The timing of the injury makes the decision tricky. There is little margin between matches at this stage of the season, and players often have limited recovery time.

For Tierney, the next 24 hours could determine whether he takes part in one of the biggest fixtures of the season. Until the manager confirms the situation, the defender remains a doubt heading into Sunday’s game.