Manchester City beat Napoli 2-1 in their Champions League Group F match on Tuesday, maintaining their 100 percent record after three games, but Pep Guardiola's side were forced to hang on despite going 2-0 up inside 13 minutes.

City started as they left off in their 7-2 crushing of Stoke City in the Premier League on Saturday, attacking with a speed and fluency which the Serie A leaders struggled to cope with.

Raheem Sterling put the home side ahead in the ninth minute, finishing with his left foot after Kyle Walker's attempt to convert a David Silva pull-back was blocked.

Four minutes later, the in-form Kevin De Bruyne created the second, powering down the right flank and delivering a pinpoint low cross to Gabriel Jesus who made no mistake.

The Premier League leaders were producing wave after wave of attacks and the appreciative crowd sensed that this could be another massacre.

Belgian midfielder De Bruyne fired a long-range shot against the bar in the 25th minute after a swift City counter-attack, and then Jesus had a goalbound effort cleared off the line by Kalidou Koulibaly.

But then City began to lose focus, sloppily giving the ball away in dangerous positions, slowing down their breaks, and Napoli sensed that the game might not be just about damage limitation.

The Italians had an opportunity to narrow the deficit in the 38th minute after Kyle Walker gave away a penalty but City's Brazilian keeper Ederson produced a fine save to keep out Dries Mertens' spot-kick.

After the break, Napoli grew into the game, with some clever touches and smart movement troubling the City defence and John Stones needed to use his midriff to stop a Marek Hamsik shot that was heading for an open goal.

Napoli's reward came when they got a second chance from the spot in the 73rd minute, this time Amadou Diawara firing home after Faouzi Ghoujlam was tripped by Fernandinho.

Despite some late pressure from Maurizio Sarri's side, City showed some grit as they held on to secure their third straight win which leaves them on top of the group with nine points.

"We knew they played patient football and had attacking threat. We knew it would be tough but we wanted to play our football," said City defender John Stones.

"At times it was great to watch. I am upset to concede the goal we did but overall ... a great team performance. We have put ourselves in a good position (in the group). There are a lot of games to play still. This was a good test to see where we are at," he added.

Napoli are third on three points, trailing second-placed Shakhtar Donetsk who are on six.

City now on a par with Barca and Real

Napoli coach Maurizio Sarri says he believes that Manchester City are now at the same level as Barcelona and Real Madrid and can go on to win the Champions League this season.

City delivered a blistering 20 minutes of attacking football to take a two-goal lead over Napoli at the Etihad Stadium on Tuesday but had to ride out the storm after the Italians -- who have yet to drop a point in Serie A -- battled back in the second half, holding on to win 2-1.

Asked after the game if he felt City were now on a level with the Spanish giants and were capable of winning the tournament, Sarri said: "Yes, I think so.

"They are an extraordinary squad. They have tremendous physical, technical and tactical qualities and if they can maintain their physical shape they could go all the way," he added.

City top Group F with the maximum nine points from three games and are also top of the Premier League with seven wins from eight.

Guardiola's side are now unbeatean in 18 games in all competitions, 14 of them wins, since the 2-1 loss to Arsenal in the FA Cup semi-finals.

Goals from Raheem Sterling and Gabriel Jesus in the opening 13 minutes looked to have opened the door to another City rout but Napoli regrouped and Sarri said he was pleased with their response.

"You have to divide the game into first 25 mins and then the rest of the game. They deserve a lot of credit for how they started the game -- their technique, speed, movement were outstanding -- but also, we didn’t apply enough pressure," he said.

"But credit to the team for coming out of that situation against a team that is destroying everything that is put in front of it.

"I'm a bit bitter with the result but we have shown we can be competitive at this level as well," he said.