Northampton Town emerged with their heads held high as Sir Alex Ferguson's Manchester United marched into the fifth round of the FA Cup at Sixfields.
United squandered a host of chances, not least a third minute penalty saved by Lee Harper from Diego Forlan. The Cobblers goalkeeper emerged as one of his team's stoutest heroes by pulling off a string of fine saves, but goals from Mikael Silvestre, a Chris Hargreaves own goal and Forlan settled the issue.
Ferguson said afterwards: "There is always concern when the chances aren't going in early on as there is always one upset in cup football and this tie was a banana skin. Credit to Northampton who hit the woodwork twice." His opposite number Colin Calderwood said: "We had always hoped to do a little bit better than this and it is disappointing, especially the manner of the first two goals, which were scrappy." He added: "I felt the players persevered and I couldn't fault them for effort. A bonus would have been a goal for us at the end and although it didn't happen at least we had one or two good efforts.
"When my players look at the video I think they will understand how Manchester United are performing at the level they do." The early spot-kick arrived when Chris Carruthers pushed Cristiano Ronaldo, but Forlan struck his shot at a comfortable height for Harper who guessed the right way.
United missed a series of chances, with David Bellion and Ronaldo the chief culprits before they led in the 34th minute, Silvestre bundling the ball home from close range after Harper failed to deal with a Ronaldo shot.
Derek Asamoah had the Third Division side's best first-half chance but was unable to lift the ball over Roy Carroll.
Any hopes of an upset Northampton had were dashed two minutes after the restart when a Ronaldo corner was turned in to his own net by the unfortunate Hargreaves.
In the same incident, Carruthers was stretchered off with whiplash injuries.
Substitute Marc Richards rocked the United crossbar with a cracking volley on the hour, but Forlan made it 3-0 eight minutes later when Ronaldo headed back a John O'Shea cross.
The Cobblers came painfully close to a consolation, with Martin Smith almost squeezing in a 20-yard free-kick two minutes from time, before Paul Harsley's late drive was spilled by Carroll only for Asamoah to hit the post with the rebound.