And although the majority of supporters were decked out in the red of United, each of the home side's forward forays was also cheered.
Khama Billiat looked especially lively up front and provided Reds centre-back Scott Wootton with a stern test in the first 45 minutes. Billiat will have been disappointed when he dragged wide in the 20th minute and again later when he passed poorly with Ajax storming down the pitch on the counter-attack.
At the other end, United's only real chance of the first half came on 34 minutes when Hernandez met Wootton's cross with a firm header. But the Mexican could only watch as Ajax goalkeeper (and former Liverpool player) Sander Westerveld dived to his right to push the ball around the post.
Michael Carrick's probing pass rolled agonisingly across the six-yard box just before the interval - neither Hernandez nor Antonio Valencia could apply a finish - but in truth it was the home side who could hold their heads highest as they left the pitch at half-time.
The second period began brightly, with Valencia causing havoc down the right flank in the first 15 minutes. No clear-cut chances were created, however, until Kagawa nodded wide from close-range, the goal at his mercy.
With 22 minutes to play, Sir Alex made a quadruple substitution in a change that handed 18-year-old Nick Powell his first taste of Reds action, as well as valuable minutes to Bebe, Ryan Tunnicliffe and Jesse Lingard.
Ben Amos excelled on 75 minutes when he saved smartly down by his near post to deny Thembinkosi Fanteni from 18 yards. It was a moment that sparked a surge of confidence in the Ajax side, who continued to push forward in