back into the area and Karim Haggui rose highest to thump home a header.
The Tunisian international was one of eight substitutes brought on by the hosts and another, Didier Ya Konen, twice brought sharp saves from De Gea after the interval. United might have levelled when Rooney released Chicharito, but Zieler did brilliantly to fend away the Mexican's effort with his right foot.
United's chances of taking a positive result were dealt a blow shortly after the hour when Hannover established a two-goal lead with a simple, yet impishly-taken goal. Lars Stindl clipped a cross into the six-yard box and Mohammed Abdellaoue opted to line up an outrageous back-heel flick which nestled inside De Gea's post.
The Reds' riposte was swift. Nani's surging run was clumsily halted, 25 yards from goal, giving Rooney the perfect opportunity to whip a wonderful free-kick over the Hannover wall and inside the static Zieler's post.
Both Anderson and Antonio Valencia were introduced in place of Vidic and Chicharito, and the Brazilian midfielder threaded a neat through-ball to tee up United's leveller. Rooney latched onto the pass, rounded Zieler and tumbled after contact from the former United stopper.