The caretaker boss was satisfied with his side's performance, as they came back from behind to earn a point at Stamford Bridge, but conceded they looked vulnerable on occasions
Two goals from Oscar helped the titleholders to a comfortable lead, but the Bianconeri fought back as Arturo Vidal and Fabio Quagliarella eventually tied the scores at Stamford Bridge.
"We did very well, we were in good physical condition and that's how we turned the match around. We were losing by two goals but came back fighting," the interim coach said after the match.
"We also know we have weaknesses that we have to work on. We could have won it; we could have lost it as well. But that's football. I'm just happy that tonight we proved we can play at this level."
Carrera then went on to praise Arturo Vidal, who pulled one back for his team just minutes after an injury which seemed to force him off.
"Vidal reflects the soul of this team. He was injured and we were going to take him off, but he said he was alright and he came back to score a goal – it just shows our strength."
Juventus take on Shakhtar Donetsk on October 2 in their second Group E game.