SAN SEBASTIAN, Spain (REUTERS) - Manchester United missed a chance to move to the brink of qualification for the Champions League last 16 when Robin van Persie twice hit the post in a 0-0 draw at Real Sociedad in Group A on Tuesday.
The Netherlands forward almost scored moments after replacing Wayne Rooney just after the hour when his far-post shot cannoned away off the righthand upright.
United were awarded a penalty for what looked like a blatant Ashley Young dive in the 69th minute but Van Persie's powerful strike hit the same post and bounced away to safety.
United's Belgium midfielder Marouane Fellaini was sent off in the 90th minute after picking up a second yellow card.
The English champions stayed top of the group on eight points from four of six matches, with Bundesliga side Bayer Leverkusen on seven and Shakhtar Donetsk on five after they drew 0-0.
Sociedad are bottom on one point and are on the verge of elimination in their first foray into Europe's elite club competition in a decade.
United manager David Moyes initially deployed Javier Hernandez up front with Rooney with Ryan Giggs pulling the strings in midfield and the visitors dominated the early stages without creating much genuine danger.
Sociedad started to settle as halftime approached and fullback Alberto de la Bella curled a low effort just past the post in the 45th minute.
Hernandez fluffed one of the clearest openings of the game a minute after the break when the Mexican shanked his effort over the crossbar from close range with Sociedad keeper Claudio Bravo floundering.
Rooney and Hernandez toiled for an hour before Moyes made a double substitution, bringing on Van Persie and Young and United seemed to find the cutting edge they were lacking.
The referee pointed to the spot when Young went to ground despite there being little contact with Sociedad captain Markel Bergara.
Sociedad might have snatched victory when Xabi Prieto's shot was deflected just over the bar by Carlos Vela 15 minutes from time but a draw was ultimately a fair result.