Heidelberg - Pep Guardiola says his Manchester City side effectively face the first of "five finals" in the Champions League group stages at Hoffenheim on Tuesday following defeat in their opening game.
City's 2-1 loss to Lyon in Manchester a fortnight ago meant they arrived in Germany desperate for a win over Bundesliga side Hoffenheim, who are hosting their first ever Champions League home match.
"We have five finals now. We lost the first game, so now we must win each one -- tomorrow is the first final," Guardiola said when asked about the Lyon defeat.
"Maybe we need to suffer a bit.
"It (the Champions League) is a top quality level competition, each team is so good and it makes things complicated.
"We weren't so good against Lyon in the first half.
"Since I have been here, we have always qualified comfortably (for the knock-out stages) and maybe this shows what a tough competition it is."
Kevin de Bruyne trained with the City team before they left Manchester on Monday, for the first time since suffering a knee injury in August, but the Hoffenheim game comes too soon for the Belgium playmaker.
Guardiola will be back on the touchline again after serving a ban for the Lyon game following his sending off in last season's quarter-final defeat to Liverpool.
"I prefer to be on closer to my players, rather than in the stands," he said at a press conference in Heidelberg, neat Hoffenheim.
The Spaniard poured praise on opposite number Julian Nagelsmann, 31, the youngest coach in Champions League history, who counts Guardiola as one his inspirations.
Nagelsmann took charge aged just 29 in February 2016 and has steered Hoffenheim from the brink of relegation to the Champions League inside two years.
"We are in contact through other people, I am really impressed, he took over Hoffenheim in a bad situation and every year he is getting better," said Guardiola.
"Tomorrow is the first time his team will face mine and I am looking forward to it.
"He is only 31 and already managing a team in a good competition, I am happy to see a manager of his quality to produce some nice football and he will have a good career."