Maurizio Sarri said he was happy for Napoli after his former side inflicted a second Serie A loss of the season on Juventus, who missed the chance to move six points clear of Inter.
Although Cristiano Ronaldo scored for the eighth game in a row, it was too little and too late for the champions after goals from Piotr Zielinski and Lorenzo Insigne put Napoli 2-0 ahead on Sunday.
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There were anti-Sarri chants and banners on his return to San Paolo, but the coach was glad to see Napoli arrest their slump, even against his current club.
"I am happy for the lads, as I will always be fond of them," he told Sky Sport Italia after Juve's five-game winning streak in Serie A ended.
"If you have to lose, I guess I'd rather it be here to help Napoli get out of their current problems. I'd rather they started winning next week, of course.
"Clearly, the game takes over and you have to detach yourself from everything around that. Napoli represented a special moment in my life and it's always pleasing and emotional to be back here.
"We should have felt more motivated to break away [from Inter] rather than less, otherwise this will mean we are weak. I would hope not.
"If that situation weighed on us, even unconsciously, it means we are not ready yet."
Napoli's first home league win since October followed a midweek Coppa Italia victory over Lazio, but head coach Gennaro Gattuso is not getting carried away with his side's improvement.
"I go home tonight and will still keep thinking about the [2-0] defeat to Fiorentina, because that was just shocking," Gattuso told Sky Sport Italia .
"We beat two good teams now, fine, but we are still in trouble, still a long way back and need to keep pushing.
"I congratulate the lads for the work they've done over the last seven days, but we have to keep going like this now, do not let up, focus on Napoli 24 hours a day.
"We didn't do that well in possession today, but did far better when covering, blocking off the passes and the overlapping runs were timed properly.
"I was angry at the Ronaldo goal, because we can't let anything slip at the moment."