United are without playmaker Paul Scholes due to suspension while injuries have sidelined defender Mikael Silvestre, midfielder Darren Fletcher and forwards Louis Saha and Ole Gunnar Solskjaer.

Ferguson believed the morale and desire for victory which enabled the Premier League leaders to score late winning goals at Fulham and Liverpool in recent weeks would see them through at the Riverside.

"They (Middlesbrough) will be positive because they've got a home draw and will think they can win," Ferguson told reporters. "However, there is a great resolve among our players, you saw that at Liverpool and Fulham.

"There's no doubt that as the season goes on the team spirit is growing. It should be a fantastic Cup tie and we'll be taking a very strong squad."