Ashley Young produced his best performance for Aston Villa in some time as they defeated Blackburn Rovers 3-1 in their FA Cup tie.
Young was restored to the starting line-up after being suspended for the midweek home defeat against Liverpool having incurred five yellow cards this season.
But the England player quickly made an impression in creating the opening two goals for young striker Nathan Delfouneso and Carlos Cuellar, with John Carew netting the fourth from the penalty spot.
O'Neill said: "Ashley set up the opening two goals and he is a top-quality player who is so important to us.
"It is three years this month since he came to us from Watford and his contribution for us during that time has been immense."
O'Neill made seven changes from the side beaten by Liverpool, and Delfouneso and another youngster in Fabien Delph created a favourable impression.
O'Neill said: "I'm delighted to have won the game.
"The players are desperate to play. We utilised the squad today and the young lads, Nathan and Fabien, did very well for us."