Marcello Lippi has said he could detect "sadness" in Francesco Totti's celebrations of his 300th goal for Roma at the weekend.
Totti, who will be 39 on Sunday, achieved the landmark moment in a 2-2 home draw with Sassuolo at the weekend -- only his second start of the season.
Lippi, the forward's coach for Italy when they won the World Cup in 2006, told Radio 2: "I was at the [Stadio] Olimpico for Roma-Sassuolo and I saw Totti's 300th goal.
"There was a celebration, also with his children, but I could see a bit of sadness in him.
"I don't know if it is melancholy because it is a time in which he is not playing very much, or maybe he is starting to realise that he is approaching the end of his fantastic career."
Totti's contract is up for renewal in the summer, and there has been no indication that he will hang up his boots before his 40th birthday.
His dream of leading Roma out at their new stadium as captain, however, is starting to look unlikely, with the arena unlikely to be complete for at least three years.
Tributes have been paid to his milestone goal, with Alessandro Del Piero among those congratulating him on Roma's official website.
"Ciao Fra, this is a special moment for you and I'm delighted to be able to get this message to you," the former Juventus captain said.
"I remember many moments we spent together. We had the honour of playing for different clubs and becoming their captains, representing the great rivalry there is between these two clubs, but this has also led us to appreciate and also to respect each other.
"We won the most beautiful thing together -- the World Cup."
Complimenti a Francesco Totti per il 300° gol con la maglia della Roma. Straordinario campione e professionista esemplare! #Totti300
- Roberto Mancini (@robymancio) September 21, 2015
Inter Milan coach Roberto Mancini also paid tribute to Totti, writing on Twitter: "Compliments to Francesco Totti for the 300th goal in a Roma shirt. An extraordinary champion and model professional!"