Increasingly, United's attackers began to chance their arm. Young and Scholes had shots blocked and Rooney's free-kick struck the top of the wall, but the hosts' massed central defensive ranks proved difficult to navigate.
Valerenga responded with a Mohammed Fellah effort which hurtled over from 30 yards, but United finished the first half in the ascendancy, as Welbeck curled an effort comfortably wide from the edge of the area, had a volley deflected wide and then nodded a Rooney cross narrowly over the bar.
With five minutes of the opening period remaining, the England strike duo combined in delightful fashion as Rooney released Welbeck, only for the Longsight-born striker to lose control of the ball under heavy pressure. Then, twice before the break, Welbeck brought the best from goalkeeper Gudmund Kongshavn.
First, superb interplay between Nani and Valencia culminated in Kongshavn fending away Welbeck's arrowed snapshot, then the home stopper flung himself to his right to tip the striker's low effort around the post. Rooney glanced a superb Young cross past the post with United's final attempt of the half, but Ahmed Suleiman's header inched past Lindegaard's upright in injury-time as the interval arrived with the scoreline blank.
The deadlock might have been broken in the 50th minute, but Rooney couldn't get the requisite power or purchase on Nani's cross, and the striker's header drifted harmlessly over the bar. Fellah headed just wide from a similar position for the hosts, before Shinji Kagawa and Anderson were introduced at the expense of Welbeck and Vidic.