United were overwhelmed by a competent performance from Boro who held on to the draw after Mark Viduka canceled out Kieran Richardson's early strike.

Ferguson's men will now face a fierce battle with holders Chelsea who have the advantage of minimizing the gap between the two sides to one point if they beat Newcastle on Sunday.

"It opens the door no question about that, it's a big task now," Ferguson told Sky Sports.

"We are still in pole position, still in the lead but we'll have to do it the hard way."

Ferguson was frustrated to see a couple of his players taken off at half-time after key defender Rio Ferdinand and goal scorer Richardson picked up first half injuries.

"The injuries killed us in the first half," he said. "But that was just the bad breaks you get in football, there is nothing you can do about it."

United will now have to turn their attention towards their upcoming UEFA Champions League clash against AC Milan in midweek.