The beginning of the end for John Terry - but could he replace Jose Mourinho as manager?

Plenty have wrongly called time on John Terry's career before now, but it really does look like we saw the beginning of the end this weekend in Manchester.

The forced admission by Jose Mourinho, that Terry is a luxury Chelsea cannot afford when chasing a game, is the sounding of the first warning shot for the arrival of a time after the Blues' Captain, Leader, Legend.

Other managers learned the hard way that you simply cannot play a high defensive line with Terry in the back four – the most notable failings coming under Andre Villas-Boas and Luis Felipe Scolari.

Mourinho verbalised that issue post-match at Eastlands, attempting to turn to the positive – that Chelsea need to have their fastest defender, in Kurt Zouma, involved at such times.

He refused to be drawn on why he sent Terry to the bench, rather than the bloody-nosed Gary Cahill – but the silence spoke volumes.

Terry's game has never depended on his pace. He has carved a niche as the finest defender of his generation through a mixture of strength, native cunning, a true never-say-die attitude, and a natural aptitude for leadership that can be taught in no school.

In his most accomplished moments, he has been paired with a foil that helps fill the gaps in his game – notably the partnership with the speedy William Gallas, which is still Chelsea's greatest centre-half duo.

Cahill is no slouch, but he is not in the same bracket as Gallas when it comes to speed. While he and Terry have been a remarkably successful pairing, Cahill's future probably rests in being the slower man of the two – particularly faced with the silver bullet speed of players like Sergio Aguero.

Terry's plight is not helped by the fact that he sits within a Chelsea defence where pace is becoming an endangered species.

He has, truth been told, lost half a yard each season in the last five; though the most notable issue this summer has been the yard lost by Branislav Ivanovic – a real shock in one of the club's top performers of the last title-winning season.

Mourinho knows both of those cannot be accommodated, and many of the perceived positional failings of Cahill and Cesar Azpilicueta this season have been down to their defensive colleagues being stranded by a lack of that extra gear.

The imminent arrival of Baba Rahman will shake some of that down, moving Azpilicueta back to his natural position at right-back and side-lining Ivanovic – thus buying Terry a little more time.

His influence is still his main asset – and it is recognised that he gives a calmed assuredness to defenders around him, while passing on a steely attitude which has been worth countless points over the last decade and a half.

But the writing is clearly on the wall – and there had to be an expectation that this latest contract extension, which will see him until the end of June 2016, will be his last.

Terry is an incredibly sharp guy, and his face on the bench at City on Sunday made it abundantly clear, should anyone be in doubt, that he is fully aware of how the cards lie.

Of course, as it says at the very top of this article, many have written him off way before his time – and it seems certain he will have an extra surprise or two up his sleeve.

Perhaps his final surprise could involve something that will take the Terry that Chelsea fans have known for so long into a different phase of his career, to deliver that famed yen for leadership in a new way.

Note that after more than a decade of juggling egos, Roman Abramovich has become cute enough to always have a spare somewhere in his armoury for the increasingly unpredictable line of managers to occupy the hotseat at Stamford Bridge.

After a week where more questions have been asked about Mourinho's long-term job prospects than at any time since his return, and with no obvious spare in sight, would it be worth taking a punt now on Chelsea's next manager to go by the name of John George Terry?

Never underestimate the man.