Roberto Mancini's mood could be accurately gauged by his expression when asked whether his father, Aldo, watching his first Manchester City game, had offered his thoughts. "Not yet," the manager said. "But he will criticise me tonight."

Mancini felt his players had suffered from being "too nervous" before their first Champions League match. Those nerves were not evident during a one-sided first half but the City manager said he was glad to get the game out of the way.

"We can do a lot better in the next game," he said, looking ahead to the match against Bayern Munich at the Allianz Arena on 27 September. "We will do better because it is the second game and we will not be so nervous. This game, we were so nervous – all the players. It surprised me. Maybe it was simply desire, or the pressure to play well, but they need to understand how important it is to play simply and that putting seven or eight players forward doesn't work."

The instruction to "play simple" could have been a direct reference to Edinson Cavani's goal, originating from Gareth Barry giving the ball away with a backheel. "It could be," Mancini replied when asked whether it was intended as a criticism of the England international. "I told the guys to pay attention because Napoli were good on the counterattack but we gave away a stupid goal. You can't concede a goal like that. When we lost that ball we didn't have any midfielders in front of the defenders."

Asked if it was naive of Barry, he replied: "Yes, for sure. For 10 minutes in the second half we conceded a lot of space and Napoli looked really dangerous. We need to improve. We have fantastic players but every game in the Champions League is difficult. It's important we play simple." Mancini also commented that he had "never said we were Barcelona".

On television the Italian made the bold claim that his team would respond by beating Bayern. Later, however, he had revised that claim – but there was still a notable air of confidence.

"It will be the second game and we will be a lot more calm. All the players wanted to win tonight but we were too nervous. Instead, if we play easy, simple football we can play much better. Bayern are a fantastic team but we can win. We have a team who can win over there so I'm not worried about dropping these points at home."

Vincent Kompany acknowledged the night had an unusual feel: "It's a special occasion, everything is completely different to what we are used to in the Premier League," the defender said.