Atleti's hopes of pulling off a famous La Liga and Champions League double are still very much alive after they came from behind to win a frantic encounter at Stamford Bridge 3-1.
Following a drab first leg at Vicente Calderon last week, there was no shortage of drama on Wednesday as former Atleti captain Fernando Torres put Chelsea in front against his former club.
The Liga leaders were level just before half-time, though, courtesy of Adrian Lopez's strike before the game's end-to-end nature was encapsulated.
Thibaut Courtois - Atleti's on-loan Chelsea goalkeeper - made a stunning save to deny John Terry, with the visitors bursting up the other end and winning a penalty through Samuel Eto'o's clumsy foul on Diego Costa.
The Spain international dusted himself off to put Atleti ahead and in full control of the tie with half an hour to play.
Arda Turan sealed an impressive victory for Diego Simeone's side, who can now look forward to their first final in Europe's premier club competition for 40 years, with La Liga title rivals and neighbours Real Madrid their opponents at Estadio da Luz on May 24.
Despite his disappointment, Mourinho - whose wait to become the first man to win the famous trophy for three different clubs continues - gave credit to Simeone's charges.
He told Sky Sports: "The game until a certain minute was very equal.
"The first half was more ours than theirs, but finished 1-1, which is an open result. One minute decided everything in the second half.
"The Atletico goalkepeer makes an impossible save and in the same minute is the penalty that kills the game. I don't know if it was a penalty or not, I was too far away.
"That was the crucial minute, 2-1 against Atletico is almost impossible and after that there was only one team (in the game) - a team with morale high, knowing that with half an hour to go they have the game and the result in control.
"Congratulations to them because they are a very good side and what they are doing also in the Spanish league is fantastic."
