Manchester City manager Pep Guardiola warned supporters the club cannot achieve success in the Champions League unless they start fully embracing the competition.

Sergio Aguero scored a hat-trick as City opened their Group C campaign with a classy 4-0 win over Borussia Moenchengladbach on Wednesday in a game that had been postponed on Tuesday due to heavy rain.

But as in previous group-stage games, the Etihad Stadium was far from full, with only 30,270 spectators present in an arena that can hold 53,000 on European nights.

"Our fans, they have to know that we play for them," Guardiola said.

"It's our job, we are here, but to play without our fans, there is no reason why we are here. Our fans have to know that we need them in the Champions League.

"In the Premier League, everybody comes here, but in the Champions League the people don't come.

"We need them to compete against the best teams in the world. We can't make something good in the Champions League in the upcoming years without them.

"With our supporters and our songs, we are stronger. I think, honestly, what these players have done from the beginning, our players deserve the stadium completely full.

"Hopefully against Barcelona and Celtic (their other group opponents), it will happen."

City reached the Champions League semi-finals last season under Guardiola's predecessor, Manuel Pellegrini.

Guardiola, a two-time Champions League winner with Barcelona, also called on City's supporters to end their practice of booing the competition's anthem.

City fans have jeered the music since CSKA Moscow supporters managed to watch a game against them in 2014 despite it being played behind closed doors as a punishment for racism by the Russian club's fans.

They also felt harshly treated by Financial Fair Play sanctions meted out to City by European governing body UEFA the same year.

- Aguero admonishment -

"I was not here (to see) what happened, but they can forget it. They must forget what happened in the past," said Guardiola.

"Today the stadium is not completely full, so the only thing we can do is play good so the people watching at home say: 'Wow, next time I'm going to be there.'

"We have to be so proud to play in this competition. Not all the teams can play this competition.

"In three or four weeks coming here is the best football player ever (Lionel Messi), with Luis Suarez, with Neymar and the amazing Barcelona team, and we have to come here to enjoy it.

"The people are listening to me, so I am sure they are going to do that."

Aguero opened the scoring in the ninth minute with a near-post finish from Aleksandar Kolarov's cross and made it 2-0 from the penalty spot after Christoph Kramer fouled City debutant Ilkay Gundogan.

He rounded Gladbach goalkeeper Yann Sommer to score from Raheem Sterling's pass in the 77th minute and his replacement Kelechi Iheanacho added a fourth in stoppage time.

Despite Aguero taking his tally for the season to nine goals, Guardiola suggested the Argentina striker needed to put more defensive effort in off the ball.

"I wanted to convince Sergio that his talent in the box to score goals is natural," Guardiola said.

"I cannot teach him that, but he has to know that behind there is a team that's going to help him, if he's going to help, and that is what I want to convince him."

Gladbach coach Andre Schubert acknowledged the 24-hour delay had inconvenienced his team, but said it did not affect the outcome of the match.

"We've not been very happy the last two, three days. Everything's run against us," he said.

"It's very different to three days at home. You're in a hotel, there's the stress of travelling.

"But that's not the reason we lost to Man City tonight. There were less fans here, but the ones who were here did a fantastic job."

Source: AFP