Roberto Mancini described Manchester City's first-half performance as "very strange" after the Europa League exit to Sporting while taking the blame for the defeat personally.
City, trailing 1-0 from the first leg, dug themselves a much deeper hole as Mathias Fernandez and Ricky van Wolfswinkel put Sporting 2-0 up in the first half, but City got themselves back into it in a thrilling final half-hour as Sergio Aguero scored either side of a Mario Balotelli penalty.
City were unable to get a fourth and exited on away goals, and Mancini told ESPN: "I think the first half was very strange. We left a lot of space for them on the counter-attack and didn't play as a team in the first half."
Mancini could be seen exchanging angry words with Balotelli after the Italian had conceded the free-kick from which Sporting opened the scoring, but he refused to blame the controversial striker.
"I was disappointed with him when he conceded the free-kick, but it is not his fault we lost this game," he said. "I'm the manager, it is my fault.
"The second half was fantastic, but in the end I'm disappointed to go out like this."
Goalkeeper Joe Hart thought he had scored an unbelievable winner when his injury-time header was pushed wide of the post.
In the last of five minutes of injury-time, Hart - up for a corner - got on the end of a cross from Nigel de Jong and sent a strong header goalwards, only to see his opposite number touch it narrowly wide.
"I can't believe it - I thought it was in," Hart told ESPN. "It didn't need to get to that, but football is football. The fans were fantastic tonight and we didn't give them what they deserved in the first half.
"Hopefully we can take some positives out of the second half and move on for the rest of the season."
City now have extra time to recover with their next league game pushed back to Wednesday due to opponents Chelsea playing in the FA Cup on Sunday.
"We need to play well in every game," Hart added. "There are not many left now. We've cost ourselves with the first half but if we keep rolling now we'll be all right.
"We're one point behind the leaders of the Premier League, we're a good team and we've got nothing to worry about. We'll go in (against Chelsea) as favourites and we should be favourites."
Kolo Toure, captain in the absence of Vincent Kompany, said City had no time to rue their exit as they look to catch Manchester United in the league.
"It was important to win this game and go through, but now we need to keep our heads up," he said. "We have a really important game coming up on Wednesday against Chelsea and we have to give it all.
"For Man City now every trophy is very important so when we go out like that, it is always very difficult, but now we just need to think about the future. The past is the past."