The Uruguay international was signed from Sampdoria off the back of a strong season in Serie A and an impressive World Cup in Russia this summer.
Torreira came off the bench in Arsenal's 2-0 loss to Manchester City last time out, but Emery has hinted that the midfielder is nearing full match fitness and could be utilised in the derby.
"Yes, he is okay every day and is training good," the Spaniard told the official Arsenal website.
"He is now with the team and knowing and learning English conversation with us and can understand all the things we want to do tactically on the pitch.
"He is okay, the first match against City he played 15-20 minutes and I think this is good, I want to continue with him improving and to be okay to play."
Torreira made 38 appearances in all competitions for Sampdoria last season.