Pep Guardiola noticed it from the moment that City arrived at Turf Moor.
Aguero was in the mood to hurt the Clarets.
"From the beginning he was ready, his body language was very good…” said the Blues’ boss.
And he was right. Strikers can be funny animals. Confidence is everything, they are superstitious and can sometimes be lost in their own world as they battle to find form.
Whether any of the above could apply to City’s talismanic forward or not, perhaps only Sergio could answer, but he would admit that he has not been at his very best in recent weeks.
No matter. Sergio will always be in credit with City fans.
Whether the pressure of international football and the negative press he’s had back in Argentina took its toll or not is unclear, but things hadn’t been going his way in front of goal.
Aguero is a player who wears his heart on his sleeve so it’s not hard to tell when he’s not happy with his own form, but he looked back to his very best on Saturday.
From the moment the game started, he was alert and a threat to the Burnley defence with intelligent runs into the channels and testing Paul Robinson with a fine low shot early on.
He had a couple more efforts that didn’t find the target before he finally struck gold. Strikers don’t mind how they get their goals so the fact this was one of his scrappiest will not have worried Kun who showed razor sharp reactions to poke home Nicolas Otamendi's unintentional pass.
The celebration said everything. A weight lifted, moments later he flashed a curling left-foot drive towards the top corner but was denied by another fine Robinson save.
After the break he added what proved to be the match-winning goal and again, it was an untidy finish as Fernandinho’s cross bounced in off his shin – not that anybody was complaining!
He was again in the right place at the right time. With a smile as big as a Cheshire cat, he continued to probe down the right flank and contribute right up until the 89th minute when he was substituted to a standing ovation from the travelling City fans.
"He played really well and moved really well. He had a really good game," said Guardiola.
That’s 16 goals in 17 games this season as Sergio threatens to bag his highest tally yet for the Blues.
More importantly, with Chelsea, Arsenal and Liverpool all looming on the horizon, Kun may be hitting peak form at just the right time - and that's bad news is for the rest of the Premier League.