Probably the best compliment that can be paid to Manchester United is that their reserves played with the style and panache we have come to expect of Sir Alex Ferguson's first-team. They made this an ignominious night for Leeds United, dismantling the Championship side with so little difficulty it was easy to forget that Ferguson had given his big‑hitters the night off.

Michael Owen, starting his first match of the season, scored two of the goals for a team bristling with confidence and goal-scoring danger. Ryan Giggs scored the other and, for Leeds, the final whistle must have had the effect of smelling salts. In truth, it had become apparent much earlier there would not be an upset. All the goals came before half‑time and even if they sometimes give the impression at Old Trafford that they do not entirely cherish the Carling Cup, this still represented a hugely satisfying moment for Ferguson on a night when his starting XI included no recognised centre‑halves and four centre-forwards.

Even by Ferguson's standards of experimentation, it was an eccentric selection. Michael Carrick, a midfielder once likened to Glenn Hoddle, made an unorthodox centre-half. He was partnered by Ezekiel Fryers, a youth-academy graduate making his debut 11 days after turning 19. Fryers is normally a left-back. When he suffered cramp late in the second half, Dimitar Berbatov took over, like a modern-day Beckenbauer. With Antonio Valencia at right-back and Fabio on the left, has there ever been a more unconventional back four in United's colours?

For Ferguson to devise this team and his goalkeeper, Ben Amos, to go through the match without getting a scuff of mud on his kit demonstrates what a demoralising night it was for Leeds. Amos, usually the third-choice goalkeeper at Old Trafford, was a virtual spectator. Federico Macheda and Mame Biram Diouf, two of Ferguson's reserve strikers, played as wingers. The seven substitutes were aged 18 to 20, including five with no previous first-team experience. This was a team that ought to have been ripe for an upset – and yet Leeds never even sought to investigate.

Their manager, Simon Grayson, spoke afterwards of facing a "world-class team" but he was being economical with the truth and it was peculiar in the extreme that Leeds were so passive, as if forgetting they had eliminated these opponents from the FA Cup two seasons ago. They began the game encouragingly, with Berbatov making two important clearances from inside the six-yard area, but the Leeds challenge quickly tailed off.

Fryers, for one, must wonder whether it is always this easy. By the end, he was joined on the pitch by Paul Pogba and Larnell Cole, another couple of teenagers from the seemingly endless conveyor belt of young talent at Old Trafford. In truth, it was so comfortable that Ferguson could probably have brought on a couple of his under-15s.

The gulf between the two clubs was apparent from the start and, by half-time, it had become an exercise in damage-limitation for Leeds. A lot is made of the crowd's hostility on these occasions – predictably, several chants crossed the line of acceptable rivalry – but Ferguson had enough players with big-game experience to cope with such an atmosphere.

Berbatov was prominently involved. Giggs was magnificent in his 45 minutes before making way for Pogba. As for Owen, this was the best way possible to demonstrate why he believes he should have more time on the pitch. Ferguson sympathised afterwards, saying the former England striker was "not getting the games he deserves".

The first goal stemmed from a flowing move on the right, Giggs linking with Berbatov before Park Ji-sung turned the ball into Owen's path. The striker's first touch took him inside Tom Lees. The second was a left-foot shot through the defender's legs and just inside the post.

His shot was scuffed and a little fortuitous but his second goal could hardly have been struck more cleanly and something of a rarity, too – an Owen goal from outside the penalty area. Again, it originated on the right. Diouf, an enthusiastic runner, crossed. Owen took one touch before driving a brilliant shot into the top corner.

Leeds's big night was suddenly turning into an ordeal. In first-half stoppage-time Giggs ran at Aidan White, slipped the ball through his legs and continued into the penalty area. His shot flicked off Luciano Becchio to deceive the goalkeeper, Andy Lonergan, for 3-0.

Leeds were probably fortunate their opponents did not play with the same urgency after the interval. The truth was it was difficult to go through Grayson's team and identify one player who had stood out for the right reasons. Ferguson's experiment had worked beautifully.