After yesterday's 2-1 victory which knocked Celta Vigo off the top of the Spanish league and lifted Atletico to fourth, Atletico's coach, Arrigo Sacchi, said: "He [Juninho] does not have his place in the team because he is an attacking midfielder and his place is already occupied by Juan Carlos Valeron."
He added: "I must help Juninho, he's a player I rate and appreciate. But I have two great attacking midfielders, Valeron and Juninho, and when I play them together it doesn't work. I have spoken frankly with him [Juninho]."
The Brazilian only played 20 minutes against Celta and came up against Michel Salgado, whose tackle last season put him out of the World Cup.
Earlier in the day, the player's father and agent, Osvaldo, had said he would meet Atletico officials and hinted Boro were favourites to win his signature should he move on.
"Middlesbrough have a good chance of signing him. We will talk to [Middlesbrough chairman] Steve Gibson next week. We get on with him very well. I think they can afford Juninho," he said. "Juninho has not spoken to anyone yet. We have a meeting with Atletico on Monday and we will tell them Juninho wishes to leave.
"Then we will start talking to clubs and we will listen to what Middlesbrough have to say. He is keen to play in England."
The Rangers manager, Dick Advocaat, has dismissed reports linking the former Celtic striker Pierre van Hooijdonk and the Brazilian winger Denilson with a move to the Premier League leaders.
Advocaat watched his side struggle to find top form in a 2-0 victory over a brave Stenhousemuir side in the Tennents Scottish Cup on Saturday. Then he took the opportunity to insist that rumours linking Nottingham's Forest striker Van Hooijdonk and Real Betis's Denilson were just speculation. The Dutchman said: "There's no truth at all. We will continue throughout the rest of the season with this squad. I am happy with the players I have got."