The Uruguay international sealed his loan move to Atletico on deadline day, while Arsenal signed Thomas Partey in a £45 million deal from the Spanish club.
Torreira had not featured for Arsenal before his switch to the Spanish capital but was immediately handed his first start after the international break as Atletico sealed a 2-0 win over Celta Vigo.
Torreira delivered a strong performance at the heart of Atletico’s midfield alongside Koke.
And Simeone has backed the 24-year-old to be a key player for his side.
‘He is a very hard-working boy, we are going to need him,’ Simeone said after the game.
‘He competes very well, he will give us a lot of strength there in the middle of the court, when he obviously picks up the pace of the game.
‘His speed characteristics, going out quickly in the circulation of the ball in the middle will generate more speed in that part of the middle of the pitch and well, hopefully he will find the best form.’
‘We knew that such annoyances could happen because it had been a long time since he played in this situation,’ said Simeone.
‘But from his first day here he showed what his characteristics were – a guy who is going to give absolutely everything.’