But Hull's never-say-die attitude, combined with United's complacency, made for a tense and thrilling finale which saw Ferguson's side scrape home by the odd goal in seven.
United got off to a flying start when they scored after only three minutes. Gary Neville, making his 550th appearance for United crossed the ball in from the right.
Cristiano Ronaldo produced an audacious flick back to Dimitar Berbatov who was hovering on the right corner of the Hull penalty area.
Berbatov touched the ball back to Ronaldo, who scored with a low left-foot shot from 15 yards which went in off the post.
Hull's height and strength caused United defensive problems as was apparent with the Tigers equaliser in the 23rd minute.
Andy Dawson floated in a free-kick from the right side of the United box and Daniel Cousin out-jumped Patrice Evra in an uneven contest on the nearside of the six-yard box to send his glancing header beyond goalkeeper Edwin van der Sar and into the far corner of the net.
United restored their lead courtesy of a glorious move in the 29th minute. Nemanja Vidic's pass out of defence found Wayne Rooney, who touched the ball off to Berbatov.
The Bulgarian found Michael Carrick racing in on the left side of the Hull box and his crisp low left-foot shot from 15 yards went in off the foot of the far post.
With the game moving towards first-half stoppage time, United made it 3-1. Nani's corner to the near post saw Ronaldo jump above three Hull defenders to head in from ten yards.
When Vidic made it 4-1 after 57 minutes - shooting home Rooney's corner right footed from seven yards, it looked as if it was going to be the second thrashing in a week for Hull.
But the Tigers roared back as the pressure they applied on United, together with the champions' lethargy, started to produce mistakes.
One such came in the 69th minute when Cousin drove a ball from the left towards Bernard Mendy on the right side of the United penalty area.
Evra was favourite to clear but, under pressure from Mendy, he headed the ball into the Hull substitute's path and his excellent chip beat van der Sar and crossed the line, despite Vidic's heroic effort to clear.
Then, in the 82nd minute, Rio Ferdinand brought down Mendy on the left side of the United box.
Referee Mike Dean pointed to the spot and Geovanni stepped up to blast his right-footed penalty beyond van der Sar and into the top right corner of the net.