GLASGOW -- Pep Guardiola praised the resilience of his Manchester City side after they fought back to secure a 3-3 draw with Celtic in the Champions League.
City won their first 10 games of the season ahead of the Group C clash on Wednesday but fell behind to the Scottish champions three times -- drawing themselves level each time.
It was the first time they had fallen behind in a match all season, and while Guardiola was happy to see his side's fighting spirit, he warned they must improve if they are to make an impact in Europe.
"Sometimes it happens during the season you go behind. It's not easy to recover one goal, imagine two, imagine three," Guardiola told a news conference. "It's a shock mentally when after two minutes you concede a goal.
"This club was 25, 26 years without playing in Europe -- in the last year it was the first time to go through more than the quarterfinals. That will be a good lesson.
"Europe is special, the teams are so strong, it doesn't matter where. And the opponents here Celtic -- it's an amazing environment and the fans ... we knew that.
"But maybe it will be a good lesson for the future. We had a little bit of problem with our build up. But the players make a real good game."
It was a thrilling clash with Fernandinho, Raheem Sterling and Nolito pulling City level each time they fell behind.
The Premier League leaders were big favourites going into the game particularly after their 4-0 victory over Borussia Monchengladbach in the week one fixtures while Celtic were thrashed 7-0 at Barcelona.
However, Guardiola said Celtic are a different proposition at a raucous Celtic Park and pointed to their fantastic home record in Champions League group games.
Guardiola said: "It was a fantastic game for the spectators. We scored three goals away but we didn't win. The team gave an amazing effort to recover that situation, it wasn't easy here in this stadium where in the last 24 games at home they've lost just three.
"Here, prestigious teams in Europe find it difficult to win. Manchester City don't have the history in Europe - we have to create it and it will maybe be a good lesson for our future how important it is to start well.
"In the second half, except for the first five, ten minutes, we played good. They don't create many, many chances and we created enough to win the game. But we knew when the fourth team in the pot is Celtic you immediately realise how difficult it is to go through.
"But talking about the performance, the guys how they fight, it doesn't matter the mistakes they tried until the end to win the game."
The draw meant that City didn't equal the club record of 11 straight victories but Guardiola says they will learn a lot from not winning.
"I didn't speak about the record with my players," he added. "I'm pretty sure they know we are not going to win every game this season. It is impossible. Not even the best team in the world.
"We didn't lose the match. In the Champions League you cannot dominate for 90 minutes."