Pep Guardiola hailed Phil Foden's growing maturity after the youngster played a key part in Manchester City's Champions League quarter-final success.
The 20-year-old twice settled City nerves with winning goals in both legs against the German side.
On Wednesday he struck from outside the box as City came from behind to win 2-1 at Signal Iduna Park and complete a 4-2 aggregate success.
His contributions ensured quadruple-chasing City progressed to the last four for only the second time in their history and the first since Guardiola took charge of the club five years ago.
Guardiola has gradually eased Foden into the side over the course of his tenure and the England midfielder now looks ready to take command on the big stage.
"You have the feeling that he is a guy who never hides," said Guardiola, whose side will play Paris St Germain for a place in the final. "He always creates something. He is dynamic offensively, defensively with quality in the smaller spaces.
"He is learning right now not to take just one touch. He is able to make more touches when making decisions.
"He scored two important goals. The second goal in the Etihad and now helped us to be in the semi-final. We knew it from the beginning and how he grew up.
"In the quarter-final of the Champions League, he was the important player to go through to play against PSG."
City suffered an early scare in Germany as the impressive Jude Bellingham fired Dortmund into an early lead. The 17-year-old England international's deft finish not only levelled the tie on aggregate but gave Dortmund the edge on the away goals rule.
After the frustrations of recent seasons, including exits at the quarter-final stage for the last three years in succession, City's nerve was put to the test.
They came through with two goals in the second half. Riyad Mahrez first struck a confident penalty after Emre Can was controversially adjudged to have handled and Foden found the net from distance, via the post, 15 minutes from time.
Guardiola felt City had survived a big test and cleared a psychological barrier.
"Now we are incredibly happy," he said. "Three times in the last five years we have been out of the Champions League on away goals. The margin is so minimal.
"When that has happened, not everything is a disaster. You should not be judged on one season when we are there in the Premier League every day.
"In the Champions League, getting to the last 16 is a big success, the quarter-finals a huge success, semi-finals – no words to express that.
"It is just the second time this club has been in the semi-finals. It has never reached the final.
"We are not mature enough in this competition but the players learned a lot in the last seasons and we are making steps forward for the next seasons to say, 'OK, we can play semi-finals. We were there once, maybe we can do it again'.
"Here we broke this bridge, mentally for all the club. It was a big relief and it is so important."
