The clock starts to tick on Terry's Chelsea career
John Terry was out of the picture at the moment when the reality of his 34 years must have coursed through him like a lightning bolt.
His instincts had told him to head out of his penalty area to deal with the elusive presence of David Silva. And it was from there that he viewed the dreadful, yawning reality of the game's decisive moment: the chest-cushioned control by Sergio Aguero of Yaya Touré's return pass, the Argentine's weight transfer and swivel towards goal and, as Terry raced back to make amends, the side-footed finish. He was too late. Several seconds too late.
Terry said in pre-season, when his manager's pursuit of Everton's John Stones became so transparent, that he was "not naive enough" to consider himself irreplaceable and that he needed to maintain the form of last season, when he played every minute of Chelsea's Premier League campaign. "I know that if I don't, the manager will take me out of the side and replace me," he observed. That kind of talk is cheap when no notion lurks of what we witnessed yesterday: Terry emerging from the interval to sit in a dugout, with a face that told a thousand stories, after Jose Mourinho had broken the habit of a working lifetime and substituted him in a Premier League game.
Defenders will tell you that age does not creep up on you at such a remorseless level of football as this. It simply hits you like a juggernaut.
This may not be such a defining moment as all that for Terry, the outstanding Premier League centre-half of last season, but it was notice of the challenge these next nine months will represent. Mourinho's description of the "fragility" of Chelsea's defence will have cut Terry all over again when he read it last night. Just like the manager's response to whether what had just happened on the pitch outside was the worst he had seen in his two Chelsea reigns. "Defensively?" Mourinho replied. "I don't know…"
There have been few 45 minutes quite like that for the captain; City operating with a pace and sense of intent that made them unrecognisable from the side of last season.
The Raheem Sterling component to the challenge was even less predictable. The 20-year-old's early suggestions that £49m will not look such a lot of money come May were born out of his movement off the ball as much as his time on it. Sterling drifted around the front line, seeking out the small pockets of space, leaving both Terry and Cahill looking unsure at times whether to leave or follow.
It was the first time since May 2013, against Aston Villa, that any Chelsea manager had substituted Terry and not the kind of twist that will be music to the ears of Everton and Roberto Martinez, working resolutely to keep Stones from Stamford Bridge's clutches.
For Mourinho, the anxieties stretch beyond the evidence, also exploited by Swansea the week before, that his defence are vulnerable to the through ball delivered at pace.
Terry did not stop to discuss the afternoon as he left the Etihad. The difficulty with these moments is to deal with the searing scrutiny that they bring. There will certainly be more imperious performances ahead. But when a weakness is discerned in the Premier League, the drive to exploit it is remorseless. The captain's season will be a long one.