The Manchester United manager was angry after Christian Eriksen was ruled out until at least late April with an ankle injury.
Forest trail 3-0 from the first leg of the League Cup semi-final.
Ahamada has signed a three-year-deal with the Eagles which showcases the faith they have in the midfielder. The 20-year-old France youth international began his career in the Juventus academy before moving to Stuttgart two years ago. Ahamada has been deployed all across the centre of midfield this season and will add depth to Patrick Vieira's squad.