City were made to work hard for the victory, with Phil Foden’s late strike giving us a slender advantage going into next week’s second leg at Westfalenstadion.
Guardiola says given his side were under the most pressure, the result was a good one - and the City boss promised to go to Germany next week and play to win.
“Second half was better [than the first,” he said.
“When you win 26 games in 27 and they are not winning the Bundesliga, the pressure is on our shoulders. Everything is guaranteed for us. Everybody believed we would win.
“We had an incredible commitment and desire to go through.
“Now we fly there, 2-1, always they score but we will adjust a few things we could not do today.
“We will watch the game in a calm way, the best way possible, and see what we can do better.
“We will go there to win the game. I ask the players to win the game. We did it and now we go to Dortmund not to defend.
“We will adjust our pressing, adjust our build up and play 90 minutes to try and reach the semi-final.”
Watch Pep's post-match press conference in full via the video above!