MANCHESTER, England -- Pep Guardiola doesn't believe there is any reason why Manchester City can't win both the Premier League and the Champions League.
However, the City boss says they have to improve massively in both competitions this season or they will finish without silverware.
Premier League sides have struggled in Europe in recent seasons with Chelsea the last English team to reach a Champions League final in 2012, when they beat Bayern Munich on penalties.
Guardiola insists his side can complete a European and league double similar to the achievement he pulled off twice during his time at Barcelona.
Speaking ahead of the Group C opener against Borussia Monchengladbach at the Etihad, he told a news conference: "[Manchester] United won the Premier League and arrived in the final of the Champions League against Barcelona twice [in 2009 and 2011] and against Chelsea [in 2008], so why not?
"Why can you not win today and win in three days? I would like to know why? Why should we not try to win the games? Why not?
"It is physical, yes, but it's the same games in Spain or Germany. Maybe I will answer when we arrive in February, March, April and the players are dead -- they have no more energy or we have a lot of injuries but after four Premier League games, why can you not compete every three days? I think we can do that."
Guardiola has made a flawless start to his City career winning his first six games in charge and opening up a two-point gap at the top of the Premier League.
His side won plaudits for their brilliant performance on Saturday in the Manchester derby when they dominated Jose Mourinho's United for large parts of their 2-1 win at Old Trafford.
But Guardiola said City could easily have lost that game and says they are still a way from challenging the leading sides in Europe.
"I will try to be honest, asking me to win the Champions League this year, right now with Manchester City you have to be a really good coach. I will try," he added.
"I try to do my best and analyse the bad things we did in the last game and improve because always you can do better.
"We did good things in the last game but always you can be better. Whether we achieve or not achieve at the end of the season it is because the others will be better than us."
The Catalan has also played down City's good start to the Premier League and says their performances so far are not good enough to win the title.
"We are now after four games in the Premier League, I would like to tell this brilliant audience and our fans the way we are first in the Premier League, the way we have played until now, it will be not enough to win the Premier League so you have to improve," he said.
"We have to improve to win the Premier League. Of course we are so happy for the results, for the numbers, but it is not enough.
"We have to improve. But it is normal. All the teams have to improve. Especially when the managers are new.
"When you see Liverpool, or Tottenham with Pochettino, they are clear what they do in 90 minutes. The new managers like United or us or Chelsea, I realise how tough it is."