Pep Guardiola was delighted to belatedly take Manchester City into the Champions League semi-finals but acknowledged his side were potentially a refereeing decision away from another painful exit.
City had lost in the last eight in each of the prior three seasons, beaten by Liverpool, Tottenham and Lyon.
The Spurs defeat was particularly painful, with Fernando Llorente scoring a contentious goal at the Etihad Stadium before a last-gasp Raheem Sterling winner was disallowed.
On Wednesday, at Borussia Dortmund, a handball call went in City's favour as Emre Can was penalised and Riyad Mahrez's spot-kick - his first Champions League goal since September 2019 - cancelled out Jude Bellingham's opener.
"This competition is nice but, at the same time, it's so unfair," Guardiola told BT Sport after a 2-1 away win.
"We are judged; if we are out, the season is a failure, it's a disaster, when you play 11 months for the Premier League, for the cups, for everything. This is the competition.
"Look, today it was a penalty with the hand. Maybe it could be not given.
"And we were out for a hand against Tottenham in the quarter-finals, when it was not given, incredible hands from Llorente. That's why this competition depends on these situations."
Mahrez's equaliser set the stage for Phil Foden to make sure of his side's progress, sending City into the last four for the first time since 2015-16 - also the last time Guardiola, then Bayern Munich coach, reached this stage.
Despite this drought, the 4-2 aggregate triumph - which sets up a tie against Paris Saint-Germain - saw Guardiola equal Jose Mourinho's record of eight appearances in the Champions League semis.
He added: "I'm incredibly happy for this club, this organisation, our chairman, our players, of course, our fans, everyone.
"It's the second time we've got to the semi-final. There's not much history in our club here, but we start to build it."
There are two English sides in the last four for the second time in three years, with Chelsea joining City.
The sides will also meet in the FA Cup semi-finals this weekend, with Guardiola's men continuing their pursuit of an unprecedented quadruple - a challenge he is still reluctant to discuss.
"We are in the Premier League; we need three games to be champions," he said. "We are in the semi-finals of the Champions League. We are in the semi-finals of the FA Cup. We are in the final of the Carabao Cup.
"Honestly, it's incredible what we have done. Now we just recover, celebrate tonight, and after we'll see happens.
"One game at a time. We never speak about the four titles. One game at a time. Every competition we play, we try to win it. This is what we have to do. It's simple. There's no complication about that."
Ilkay Gundogan, who had a game-high 120 touches and only lost possession 11 times, said: "It means a lot, to be honest. I think this club, this team deserves it.
"We are grateful for being still in a great competition, reaching the semi-finals for the first time with this team. Obviously we are very happy about it."
The midfielder added: "We proved ourselves I think today that we are ready to fight also in the semi-finals."