United's Champions League defence got off to a frustrating start, as Villarreal's stifling approach yielded a goalless draw at Old Trafford.
Both sides struck the upright in the second half as the game opened up, but not even the return of Cristiano Ronaldo as a substitute could provide the inspiration required for United to overcome the Spaniards.
Following Saturday's defeat at Liverpool, Sir Alex Ferguson freshened up his side with six changes. Jonny Evans and Gary Neville replaced Nemanja Vidic and Wes Brown in defence, while Ji-sung Park, Darren Fletcher, Owen Hargreaves and Nani comprised an entirely new midfield quartet.
The Reds' reversion to a 4-4-2 saw Wayne Rooney back upfront alongside Carlos Tevez, with new signing Dimitar Berbatov ruled out entirely by a slight knee injury sustained during his debut.
Despite the wholesale changes, United fashioned the first opening after eight minutes. Hargreaves' left-wing corner evaded everybody, including Villarreal 'keeper Diego Lopez. Fortunately for the flapping Spaniard, his attempts to claim the ball were enough to put off the unmarked Rio Ferdinand, who could only mis-hit his effort, allowing the chance to pass.
Lopez did muster a fine save from Tevez's powerful 25-yarder, but the visitors were lucky to survive two decent penalty shouts when Park was twice brought down inside the area. An effort from Rooney - from the halfway line on the stroke of half-time - perfectly summed up the mood of frustration inside Old Trafford.
Villarreal emerged late for the second half, continuing the theme of doing all they could to stifle United. They almost nicked a lead, when Guille Franco sent a cheeky backheel against van der Sar's post, prompting the introduction of substitutes Ronaldo and Anderson to try and inspire some penetration.