Celtic boss Ange Postecoglou has provided a concerning update regarding the fitness of captain Callum McGregor, following last night's Champions League defeat in Germany.

What's the word?

As per the Daily Record, the title-winning coach shared his concern regarding the Scotland international, with the midfielder having been forced off inside the first half with a knee injury during that loss to Bundesliga side, RB Leipzig.

The former Yokohama boss stated: "It doesn't look good, we were a bit unlucky with the goal. He (McGregor) was about to have a shot and something happened between his knee, he put an enormous effort to chase back and it was his toe poke which put the guy through. Looking at him, it doesn't look good, but I will see what the doctor says."

As the 57-year-old alluded to, it simply wasn't the skipper's night as it was his uncharacteristic mistake that lead to Christopher Nkunku's opener, with the playmaker courageously trying to make amends by chasing back in an attempt to deny the dynamic Frenchman.

Real blow

On what was a frustrating evening for the Old Firm side as they saw their hopes of progression dealt a significant blow, the major concern will be that of McGregor, with it now an anxious wait to see just how long the 29-year-old will be out of action for.

Not only a real leader in the dressing room - having been handed the armband last summer following Scott Brown's departure - the £7.2m-rated ace also offers real quality in the engine room, having thrived in a deeper role in recent seasons, notably earning a place in the Scottish Premiership's Team of the Year last term.

The long-serving ace has been a real servant to the Glasgow side over the years, having racked up an impressive haul of 58 goals and 69 assists in 389 games in all competitions, winning a plethora of major honours in that time.

To lose such an experienced figure could well have a sizeable impact both on and off the pitch, with the £20k-per-week gem someone who "leads by example" - in the words of Postecoglou - in a squad that is largely filled with relatively recent additions.

Equally, there may also be concern over who will adequately fill the 49-cap machine's place on the pitch, with summer signing Oliver Abildgaard having only made a brief impact for the Parkhead outfit to date - with just two substitute appearances to his name thus far - while fellow new acquisition Aaron Mooy is also currently injured.

While this weekend's clash away at St Johnstone will hand the chance for someone else to shine - with McGregor definitely unavailable due to suspension - moving forward it could be a real blow not to have such a key asset in tow.