Atletico Madrid's players are angry after Jurgen Klopp accused them of play-acting and trying to get Sadio Mane sent off in Liverpool's 1-0 defeat at the Metropolitano, dressing room sources have told ESPN.
Klopp said that he substituted Mane at half time in the Champions League round of 16 first leg game to avoid the Senegal forward receiving a second yellow card.
"It's part of football, I don't like it," Klopp said in his postmatch news conference. "The plan was to get Sadio out of the game with a yellow card.
"I was afraid that his opponent would go down if Sadio only took a deep breath. After 30 minutes, three Atletico players were on the ground, not even injured."
There was more criticism from Liverpool's players, with Andy Robertson having said the home side "started falling over and getting under the skin a bit" after Saul Niguez's fourth minute goal, while Virgil van Dijk said: "That is the way they play, that's Spanish football."
ESPN has been told that Atletico's players are surprised by the complaints, and said it is important to be "gracious" in defeat as well as in victory, and that Klopp should focus more on his own team's shortcomings, given that they "didn't get a shot on target in 90 minutes."
Klopp also suggested that the home side's players and fans had over-celebrated, with the second leg to come in three weeks' time.
"They got a result, the stadium wasn't here to see sensational football, they got the result and so they are happy," he said. "There are a lot of happy faces tonight from Atletico.
"It's only 1-0, we're not 5-0 down. We don't think it will be easy at our ground. For all Atletico fans who can get a ticket for the game, welcome to Anfield."
Atletico coach Simeone had been under huge pressure after a poor run of form going into the game saw them take just one win in seven matches, leaving them 13 points off the top of La Liga, and out of the Copa del Rey having been eliminated by third-tier Cultural Leonesa.
Sources close to the players told ESPN that they had never seen Simeone as unhappy as in the last month, but that the coach's mood -- and that of the dressing room -- have been transformed by Tuesday's result, while they accepted that "there is still the return leg to come" on a night when Anfield will be "a cauldron."
Later on Wednesday Atleti president Enrique Cerezo spoke at an event at the EFE news agency's headquarters in which he discussed Anfield.
He said: "Anfield is a great stadium, they have magnificent fans, but the last time we played there, I was president in that game too... if they had to pass a technical inspection here, they wouldn't do it in their lives. And they keep playing there. It's old."