In football, there's a fundamental rule that should apply to every player, regardless of stature: if you're not fully fit, you shouldn't be on the pitch. That principle is now at the heart of a pressing concern for Celtic, as club legend Martin O'Neill has revealed that captain Callum McGregor is battling an ongoing injury and isn't at 100%.

McGregor, the inspirational leader and serial winner, already missed crucial fixtures last month—including the dramatic cup quarterfinal win at Ibrox—due to a persistent issue. As the season builds toward its dramatic climax, that same niggle appears to be lingering, and the consequences are becoming visible on the pitch.

Supporters have likely noticed the skipper hasn't been his usual influential self in recent outings. Against Dundee at Dens Park on Easter Sunday, his current vulnerabilities were laid bare. He was too easily brushed off the ball, dispossessed in key areas, and lacked his trademark fluency and urgency. Celtic narrowly got away with a result, just as they did the previous week against St Mirren, where opponents repeatedly sliced through a midfield that a fully-fit McGregor typically commands.

This isn't an overreaction; it's the observable truth. McGregor remains a terrific leader and a vital player for the club, but playing through injury risks becoming a detriment to both the team and the player himself. In the high-stakes environment of a title race, every single performance counts. The hard and fast rule must apply: if you aren't fully fit, you shouldn't be playing—captain or not.