Massimiliano Allegri was worried by Juventus' defending in the 3-0 win over Chievo after the visitors racked up 15 shots.
Gonzalo Higuain and Paulo Dybala were on target following Perparim Hetemaj's own goal in Turin, with Juve making it three wins from three in Serie A this season.
Next up is Tuesday's Champions League showdown with Barcelona at Camp Nou and Allegri knows his side must improve defensively.
"We allowed a few too many shots on target, that is something we need to work and improve on, but it was good to keep a clean sheet," the Juve coach told Mediaset Premium.
"Once Chievo started to lose intensity, our quality took over. It's only natural that when the opposition doesn't run as hard, it opens up more spaces.
Saturday night and we're doing alright! September 9, 2017
"In order to defend, you need everyone to work hard and make sure we don't allow so many chances.
"Last season we conceded few goals and allowed very few opportunities too. It depends on how hard they work when the opposition has the ball.
"If you don't concede, then it's frankly rare that Juventus don't score goals. You need to do well defensively and in attack to win trophies, so we got it wrong defensively in the Champions League final with Real Madrid and that is why we lost."
The only downside for Juve was an apparent injury to Mario Mandzukic, who was taken off late on.
There was no update on his fitness, but the Croatia international could be a doubt for the midweek match in Spain.
