Aleksandar Kolarov is a man who has plenty of experience, but against Celtic in the Champions League on Wednesday evening, it's safe to say he didn't have one of his better games.

The Serbia international was played alongside Nicolas Otamendi and the duo looked seriously shaky throughout. Whether Celtic would have scored three times if Vincent Kompany was playing is a topic for another day, but this time, it just didn't work.

Kolarov had been pretty good before the Champions League tie on Wednesday evening, but many were wondering why John Stones was on the bench if he was fit and ready. But that was Pep Guardiola's decision and ultimately, it came back to haunt him.

So with all that in mind, here's THREE reasons why Kolarov at centre-back just won't work for Manchester City...

He's just not quick enough

A 30-year-old left-back, Kolarov has never been known for his blistering pace, but in the game against Celtic he looked seriously slow.

We're not trying to say that all centre-backs need a massive amount of pace to get them through games - after all, there are plenty that are good enough at their jobs to manage without - but against Moussa Dembele and co, Kolarov really struggled to keep up and his weaknesses were exposed on more than one occasion.

Let's just say if he starts the reverse fixtures, the Bhoys' front-line won't be too disappointed at all.

Inconsistent

In what has been one of the most unlikely tactical moves since Guardiola arrived at City, Kolarov has spent much of the season playing as a somewhat makeshift centre-back. We know what ingredients make a fantastic defender and the key is consistency.

Look at Wes Morgan and Robert Huth last season for example - they were solid each and every week. But against Celtic, Kolarov was just far too inconsistent and his sliced clearance led to the third Celtic goal.

City have better options

Kolarov's emergence at centre-back has somewhat of a likeness to Rooney's exile to midfield at United - he can't get in the side in his actual position. But with players like Tosin Adarabioyo, John Stones, Nicolas Otamendi and even Pablo Zabaleta and Fernando all capable of playing centre-back, City should just pick someone else.

Vincent Kompany is still to come back and it's safe to say he's more than likely expected to go straight back into the first-team upon his return, but right now, why not give someone like Adarabioyo a shot?