Juventus coach Massimiliano Allegri criticised his players for letting their guard down and losing 2-1 at arch-rivals Inter Milan after taking the lead in the second half at the San Siro.
Inter captain Mauro Icardi headed in from a corner two minutes after Stephan Liechtsteiner had given Juve the lead, and substitute Ivan Perisic glanced home the winner to end the champions' 100 percent start to the Serie A season.
"We couldn't even hold on to the lead for two minutes," Allegri told Sky Sport Italia. "We were sluggish and complacent and dropped our intensity. This defeat has to burn within us and teach us a real lesson and get our feet back on the ground."
Allegri also defended his decision to start without 90 million euros ($100.41 million) signing Gonzalo Higuain, who came on for Mario Mandzukic with 16 minutes left to no avail.
"For me our preparation was correct, and next time we will play without Mario. We have had top opponents in our first four games and, although it would have been wonderful to have taken 12 points from them, this is not a tragedy," said the coach.
"It was a dirty, rough game and a real battle. We needed more determination and hunger to bring home the result, especially once we had gone in front."
Inter coach Frank de Boer praised his side for not letting their heads drop after conceding the first goal.
"We talked a lot about this, as we have gone behind and lost our heads three or four times this season. It's even worse if you're playing against Juve," said the Dutch coach.
"This time we stayed focused and did not stray from our approach and it really paid off."
De Boer had endured a difficult start with Inter since succeeding Roberto Mancini in the close season, taking four points from their first three league games and losing 2-0 at home to Israeli side Hapoel Beer Sheeva in the Europa League.
The former Ajax Amsterdam coach said they still had work to do to ensure their victory over Juventus was not a one-off.
"It was a fine performance from the whole team and that's how it should work, the whole side has to move in the same way, but we need to do it every week," he said.
"It's always nice after victories like this against the best side in Italy to think of such matters, but the most important thing is to prepare for our next game with Empoli."
(1 = 0.8963 euros)
(Reporting by Richard Martin; editing by Ken Ferris)