A 1-1 draw in the semi-final first leg away to Real Madrid means the rematch at the Etihad Stadium on Wednesday 17 May will be decisive.
The Swiss defender says they cannot afford to make any mistakes against the current holders but can’t wait for an appetising second leg.
“It’s one game out of two,” Akanji said after the draw at the Santiago Bernabeu. “We’ve got to bring our best game next week.
“We need to defend really well and clear in our attacks. We can’t make any mistakes and be smart.
“We’ve been working all season long to be in a position like this. It’s a big game - it doesn’t get much bigger.
“The atmosphere should be great - it’s a Champions League semi-final and the last game at home in the competition this season. I’m really looking forward to it.”
Akanji lined up on the left side of defence and was wary that Real have the quality to punish any mistakes.
Both sides’ goals came from long-range with Vinicius Junior firing the home side ahead before Kevin De Bruyne levelled with a superb 25-yard strike.
“If you make one mistake you get punished immediately,” Akanji said. “It’s why both teams always need to be ready. “There was a little bit too much space for a player like Vinicius or Kevin.
“We made a couple of mistakes, but they sometimes put the pressure on us so it’s not easy to play away and you lose the ball sometimes.
“[Pep Guardiola] wants us to play perfectly and we demand it from ourselves as well. Mistakes happen but it’s important even if we lose the ball we defend together as a team.”
Despite falling behind, Akanji said he and his team-mates never lost belief in Madrid as De Bruyne‘s equaliser extended our unbeaten run to 21 matches in all competitions.
“They’re really dangerous in transition and are really calm on the ball at the back,” he said.
“We kept the game alive in the second half and it was a great strike by Kevin to make it 1-1. We kept the belief and we are really happy we scored the equaliser.
“We looked at the videos of what happened last year, and we’ve learned. We did it a lot better.
“It’s Real Madrid - you cannot defend everything, we did our best, we scored a goal, they scored a goal. We did a good job. It’s for sure one of the toughest games [this season].”
