Costa has been sidelined due to serious injury and Simeone went on to give an update on his striker's recovery process.
"This week he has joined [the group] and participated in training," Simeone said.
"He is getting hooked [on the feeling of coming back], he is looking forward to it and he is excited.
"The doctors will discharge him when appropriate.
"We hope we can have Diego with us and when he returns, we will have a player who has given us a lot."