City had to settle for a 1-1 draw in Germany after dominating the first half, with Riyad Mahrez’s 27th-minute strike the sole reward for their total supremacy in the opening period.
The second half was a different affair with chances at both ends, and Josko Gvardiol’s header 20 minutes from time restored parity before the second leg at the Etihad Stadium on March 14.
City manager Guardiola strode on to the pitch at the final whistle and spoke to his players in a huddle, telling reporters later: “Their heads were down. I said ‘why are your heads down?’
“I said ‘get your heads up – it was really good. (If) people don’t like it, it doesn’t matter. You played the game you should play.’”
Guardiola said Leipzig, who had lost once in 20 games, should be respected by the media for their achievements both at home and abroad.
He said: “I had the feeling that the game would be decided in the second leg.
“Normally there is one misconception in football that, after the way we played the first half, people are going to say ‘how bad was the second half?’
“But why can’t you think Leipzig is a good team? They beat Real Madrid here, were much, much, much better than (against) Bayern Munich in the second half.
“I have a lot of respect for Leipzig. Always you (the press) talk about how bad one team is.
“Why not talk about how good the other one is. We have had four games in 10 days and the Arsenal one was really tough.
“We have had injured players and I am so delighted with the game we have played.”
Guardiola chose not to make any substitutions at all, despite admitting that he considered sending on England midfielder Phil Foden during the second half.
But City re-established control after Gvardiol’s equaliser, with Ilkay Gundogan going close to snatching a win before a late penalty appeal for handball was waved away.
“I was really pleased with what I was seeing,” said Guardiola. “Maybe in the second leg I will decide to be crazy and play with nine strikers!
“But I felt in this game – and I have been in this country (as Bayern Munich head coach) – that I need this type of control. With this type of situations, German teams are better than us.”
RB Leipzig coach Marco Rose said: “It was two different halves. In the first half we weren’t in the Champions League mode and weren’t aggressive enough.
“We lost second balls and it was a bad first half. But the second half was really good with more pressure on the ball and creating chances.
“We had good ball possession and scored the equaliser. So we have achieved a draw in the end and we are there.
“We are present in the game and there is much to learn from the first half we played.”