Monaco have proved too strong for City's Premier League rivals Tottenham Hotspur this season and knocked Arsenal out two years ago. Guardiola said there should be no doubts about the threat they pose.
"I'm very impressed how physically strong they are," he told a news conference on Monday in which he confirmed injury-plagued defender Vincent Kompany would not be available.
"The full backs play like wingers, the wingers play like attacking midfielders, the two strikers are fighters, they are killers in the box."
With Falcao and Kylian Mbappe proving a lethal partnership in attack, Monaco are leading Ligue 1 after banging in 76 goals in 26 games - the best return in Europe's top leagues.
City defender Nicolas Otamendi will find himself in the firing line and says finding the balance between stopping Monaco and gaining an advantage for the second leg will be key.
"It's always important to win and not concede when you play at home," he told City's website.
"Monaco play good football - they care about the ball and how they use it. They have many important players, who we have to be cautious about because they will hurt us."
While Guardiola's first season in England has not been all plain sailing, the Champions League is a competition that he has won twice as a coach with Barcelona and an environment in which he feels most at home.
"How amazing it is to be here again," he told reporters. "People think it is easy for Manchester City. A lot of big clubs are not here.
"We are lucky guys. Even in Barcelona and Bayern Munich I thought I am lucky to be here. It is not easy. Manchester City was not there for a long time.
"That is why I am satisfied to be here. All of Europe will be watching to analyse us - and kill us if we don't win."
(Reporting by Martyn Herman; Editing by Tom Heneghan)
Share
