United were boosted by the return of striker Wayne Rooney after returning from injury but the England striker wasn't at his best as he is yet to regain match fitness.
Two minutes past the hour mark, the Portuguese winger rose at the far post to head home Wes Brown's pinpoint cross from the right.
The Red Devils will be grateful to Dutch keeper Edwin van der Sar, who blocked a superb curling shot from Liedson then saved Tonel's close-range header.
In the other Group F game, AS Roma eased into a 2-0 home win over Ukraine's Dinamo Kiev.
Simone Perrotta opened the scoring after nine minutes when he connected with Max Tonetto's cross at the near post to head home.
The Italian international midfielder turned from scorer to provider in the 70th minute, releasing Francesco Totti with a deft through pass before Roma skipper fired a low drive into the bottom corner.