Now we know what has been ailing AS Roma: Francesco Totti.
When his substitute Mirko Vucinic danced into the dressing room after scoring the Inter-defeating goal that may well have turned the Roman club's season around, the leader, the figurehead, the man they are meant to look up to, was nowhere to be seen.
As the team finally came together as a unit, the Emperor had gone into the night, no doubt to brood over the waning of his powers.The Giallorossi captain turns 34 today and is into the autumn of his career - and the signs are worrying. If drastic action isn't taken soon, he's in danger of becoming a lamentable figure.
Against Inter, the self-proclaimed king of the Stadio Olimpico heard the first stirrings of discontent on the Curva Sud as groans grew louder at every failed control and misplaced back-heel.
He failed to take down a cross with his instep which would have led to a free shot in front of goal - and then when that opportunity presented itself from an indirect free-kick some seven yards out, he blasted over. The frustration was clear for everyone to see.
When Claudio Ranieri could bear it no longer - and we had to wait until the final 15 minutes - he was removed from the fray. A disconsolate figure, the No.10 marched purposefully past his coach without even a sideways glance and straight down the tunnel.
On many major occasions on his home turf, Totti either leaves the pitch to acclaim or disgrace, with a referee waving a red card at his departing figure.
This time, the whole stadium was too engrossed in this intriguing encounter to pay much attention - and with Vucinic fresh and willing to run at a tiring Inter defence whose midfield had been worked into the ground, the game shifted back towards Roma.
With the last breath about to be sucked out of the evening the Montenegrin dived full-length to head home Daniele de Rossi's curling cross. The explosion of noise would have reached down into the depths of the stadium where Totti was making good his exit - and who knows how bitter he felt.
There's a battle of wills in the Roma camp. A few days ago the coach looked an ever more isolated figure, but beating the champions has helped Ranieri reassert his reputation. Having replaced Totti at a pivotal moment, he then decided to keep Adriano on the bench Ã¢ÂÂ after the Brazilian had stripped off and looked set to come on.
When the change was made, it was Julio Baptista who was brought on while his compatriot sat stock still, back in his tracksuit. Questioned on the sudden change of heart, Ranieri said that he hadn't liked something about Adriano's demeanour Ã¢ÂÂ although the striker had spent a full 10 minutes warming up, so maybe all that exercise was too much for him.
One player Ranieri can't doubt is Jeremy Menez. A constant menace down both flanks, he also impressed through the middle when given the freedom to wander. With Marco Borriello working hard to hold the ball up, the coach should feel justified in starting Vucinic alongside the former AC Milan man with Menez in the free role.
Roma's victory has cleared much of the brooding within the camp, but it also means the time has come to rethink the whole concept of Totti as the first name on the team-sheet.
Alessandro del Piero went through a similar period before accepting that he could no longer play in every game; in doing so, the Juventus captain has extended his career towards his 36th year.
The time has come for Totti to put the club he adores ahead of his own self-love and let the younger generation of Vucinic and Menez carry the burden instead of carrying him.