Arsenal boss Arsene Wenger says he decided not to buy a new midfielder because of Francis Coquelin.
The Frenchman was impressive in victory over Southampton.
Wenger said: "I didn't go on the [transfer] market because of him, because of Frimpong, because of Wilshere coming back - he is not far away now.
"Frimpong is joining in now on Monday in full training. Diaby as well, he plays in this position. We have no real defensive midfielder because we all go forward when we have the ball."