Nottingham Forest have announced the appointment of Roy Keane as their new assistant manager.
Keane has been contemplating an offer since O'Neill was named as Aitor Karanka's successor two weeks ago.
Keane watched Forest's 3-1 win at home to Wigan Athletic over the weekend.
The Corkman spent three years as a player at Nottingham Forest from 1990 until his move to Manchester United in 1993.
O'Neill and Keane spent five years working together with the Republic of Ireland before leaving by "mutual agreement" last November.