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 search of reward. That duly arrived when Van Graan backheeled the ball over Amos for what many fans inside the stadium must have assumed was the winner.
But United never give in and under intense late pressure the locals cracked as Bebe stole the headlines with a dramatic equaliser.
United: Amos; Vermijl, Wootton, Ferdinand, Blackett; Valencia (Tunnicliffe 68), Carrick, Scholes (Powell 68); Anderson (Lingard 68); Kagawa (Berbatov 77), Hernandez (Bebe 68)