Atletico Madrid star Fernando Torres said he endured "among the worst" days in his career after he was sent off in a 2-1 defeat to Barcelona in the Champions League on Tuesday.
Torres had given his boyhood club the lead at the Camp Nou in the 25th minute, but 10 minutes his second yellow card turned the tide of the game.
Atletico were reduced to 10 men when the striker was dismissed after German referee Felix Brych booked him for going through the back of Sergio Busquets on the halfway line with plenty of teammates covering.
Luis Suarez then scored twice in the second half and Barcelona rallied to take an advantage in the teams' quarterfinal.
Torres said in the mixed zone after the game: "It was a complicated day. If not the worst day, probably among the worst in my career."
"I am sad to have left the team with 10. In a way I feel responsible for the team not winning. I am certain that with 11 it would have been totally different.
"But I am proud to play in this team. The result is not all bad. At the Calderon, anything is possible."
Later on Tuesday night, Torres took the blame for the result on Twitter.
I take responsibility for our defeat, but now more than ever let's go to The Calderón for a comeback #ForzaAtleti pic.twitter.com/Ib9YBQrvmP
- Fernando Torres (@Torres) April 5, 2016
Atletico defender Filipe Luis said Torres did not deserve to be sent off and claimed "Barcelona are protected," while coach Diego Simeone said he was proud of how his team continued to struggle against the odds.
"I feel proud of the players I have," Simeone said. "I am happy to work with a team who gives life in every game, no matter how difficult the situation, or the hurdles in the path. They try and overcome them as they can. They played a great game.
"First half until sending off it was close to very, very good. Obviously in second half Barca knew how to manage the game, use the flanks, pinned us into our area and they created chances. I am very happy to be Atletico Madrid coach, as these players have the strength to keep defending the jersey as they have."
Pressed as to his thoughts on Brych sending off Torres for two quick heavy challenges, he said: "I am not annoyed with Torres, for sure. It is for others to evaluate the decisions, just like in the past. The referees are there to do their job, and we must just focus on the footballing part. I am not saying all that I could say."
Asked if Brych was more lenient when Barca striker Suarez clashed with Atletico's Juanfran and Filipe Luis and escaped with just one yellow, Simeone suggested he thought his team had been hard-done by.
"There were more than two incidents, but I will leave it at that," he added. "I cannot open my mouth and say what I think. I must be respectful to everyone, and the referee understood it in that way. We hope to do everything possible so we can make the semifinals."
Atletico go into next week's return game with an away goal, and Simeone said there would be optimism among his team's fans that they would be able to turn the situation around.
"We are still alive," he said. "They might have scored some more goals, with the extra man. They did not. So there will still be hope and excitement among Atletico fans going to the stadium. They know it will be a nice game for everyone -- fans and players. It will not be an easy game."
Information from ESPN FC's Dermot Corrigan was used in this report.