Manchester United were held to a 0-0 draw at home by Villarreal on Wednesday as last season's Champions League winners made a stuttering start to their title defence.
United were left frustrated in their Group E opener despite the return from injury of Portuguese winger Cristiano Ronaldo, who came on as a 62nd minute substitute in his first appearance since recovering from ankle surgery.
Ronaldo was given a standing ovation by United fans, who appear to have forgiven the winger for wanting a move to Real Madrid in the close-season.
Defender Jonny Evans went closest when he headed against a post from a Ronaldo cross but Spain's Villarreal also hit the woodwork as they held out to deny United a 13th successive home win in the competition.
The last time the two clubs met in the group stages of the competition in 2005/06 they also failed to score a goal between them as two goalless draws helped knock United out and propel the Spanish club to the semi-finals.
United manager Alex Ferguson started with an unusual line-up. The inclusion of Evans and Ji-sung Park were surprises, while captain Gary Neville, who missed all of United's successful campaign last season, made his 100th Champions League appearance.
Initially United's defence was not troubled as even without the injured striker Dimitar Berbatov, denied a home debut by a knee injury, the home side pushed the Spaniards back with Rio Ferdinand, Park, Nani and Carlos Tevez all going close before the break.
Villarreal also started with two of their top players on the bench in Santi Cazorla and Marcos Senna but coach Manuel Pellegrini sent on Spanish international midfielder Cazorla at the start of the second half in an effort to spark some much needed life into his side.
And it was a pass from Cazorla which opened up United's defence and almost allowed the Spaniards to take a 60th-minute lead as Sebastian Eguren flicked a cross from Angel Lopez against the inside of the post with Edwin van der Sar beaten.
United looked laboured in attack and it took the appearance of Ronaldo, warming up along the touchline, to bring the crowd to life with the warmth of their reception confirming that his dalliance with Real Madrid had done nothing to sour the relationship.
Ferguson did not wait much longer to send on the winger whose 42 goals last season propelled United to the double and who was given almost half an hour to try and get their defence of the European title up and running.
Typically he made an almost immediate impact with a bouncing volley from a Tevez cross which was saved by goalkeeper Diego Lopez before a lovely through-ball gave Wayne Rooney the chance to set up Tevez for an effort which was cleared off the line by Gonzalo Rodriguez.
Ronaldo should then have scored himself but headed wide from a Nani cross and United's night of frustration was capped when Evans struck the woodwork seven minutes from the end.