He fielded what was almost a second string side but they were still far too accomplished for a demoralised Birmingham side that operated on an evaporating spirit.
The fact that Birmingham have become increasingly unstable was emphasised with Manchester United sealing the game in a four-minute purple patch at the start of the second half with goals from Louis Saha and Ji-Sung Park.
Saha added to his tally in the 62nd minute to demonstrate United's superiority despite a Jiri Jarosik header 13 minutes later.
Any hope of a much-needed regeneration in the Birmingham side has seemingly disappeared with the continual changes made by an ever-growing desperate manager, Steve Bruce.
There was no great expectancy of a Birmingham upset in the light of recent events and this was evident despite holding United in a goalless first half.
Hard-pressed Birmingham are now in the throes of a desperate survival situation. Unfortunately it is like a whirlpool with Birmingham rapidly being sucked down in the ever-decreasing circle of bad performances and it is not going to get any better with their next three games against Spurs, Manchester United and Chelsea.
The game predictably went the way of United as they continued from where they left off on Saturday at nearby Aston Villa despite making six changes from their winning line-up.
It was a golden opportunity for some of their promising youngsters to parade their talent and in only the fourth minute Giuseppe Rossi could have marked the occasion with an early goal.
Rossi, however, was foiled by a finger-tip save by the recalled Maik Taylor who pushed the ball onto the bar.
Taylor, who has recently been rested, distinguished himself a few minutes later when he saved a dangerous looking free-kick from Cristiano Ronaldo.
United's pressure was frightening as they confidently moved onto the attack. Taylor was powerless on one occasion when Saha's close-range header from Darren Fletcher's cross went just wide at the near post.
But Birmingham battled bravely as they attempted to swing the game in their direction. There was, however, an air of desperation about their play as the final pass was inevitably mopped up by the likes of Wes Brown and Mikael Silvestre.
Birmingham's best chance fell to the under-performing Emile Heskey just before the break. He turned to shoot only to see his effort turned away for a corner by Tim Howard.
The arrival of Wayne Rooney for the second half had a dramatic effect with United taking the lead within 40 seconds of the England striker stepping onto the pitch.
It was Ronaldo who created the opening with a low cross into the middle where Saha forced his close-range shot past Taylor.
Four minutes later Manchester United's power finished off hapless Birmingham. This time Saha provided goal provider when he set up Park to score with a rasping shot.
Rooney was given a free header by a demoralised Birmingham defence shortly afterwards with the home defence in tatters.
But it was of no consequence as United were able to increase their lead in the 62nd minute when Saha picked up a pass from skipper Gary Neville and moved back inside Martin Taylor to lash his shot past the helpless Maik Taylor for another clinical goal.
Jarosik pulled back a 75th minute goal with a glancing header from Jermaine Pennant's free-kick but it was then academic.