After a second half of resolute Chelsea defending and a Lionel Messi penalty miss, Fernando Torres confirmed Roberto Di Matteo's side's place in the final as he rounded Victor Valdes and rolled into an empty net in the 91st-minute.
The Stamford Bridge club were undone in the second minute of added time by a Laurent Depoitre header and Conte wants mistakes like that stamped out. "At the end we lost the game".
This was the first time that Eden Hazard - Chelsea's equivalent of Lionel Messi, you could say - came up against the Catalan giants. Against Atletico Madrid we were 1-0 down and then we drew and created chances to score. They have, however, still only scored 11 goals this season - the second-lowest tally in the division -which is an issue Wagner will be looking to address. Now let's move forward.
We have to be ready to fight.
But while Conte concedes his side's defeat to Manchester City was understandable, their losses to Burnley, Crystal Palace and West Ham, the latter two both in relegation danger, have given the Blues boss major cause for concern.
"We just didn't play our stuff". I have decided for this solution. Impossible to see an advantage of playing at home first. I have to be realistic, we have to face this situation with these players. The rest of Wagner's squad is thought to be fit to play as they welcome the champions.
Antonio Conte's men fell behind in the sixth minute at the London Stadium, with Marko Arnautovic edging the home side ahead.
"I think we must be very happy for the performance because from the start of the game we showed a great personality and desire to win the game against a very good team", he said.
"I like it when we have the possibility to rotate players". "You have to be on your best in terms of focus and concentration to get something out of the games when you play one of the top teams".
They also faced off in the semi-final in 2009, and this time it was Barca who benefitted from an injury-time goal.