The Mexican striker could be ruled out for up to a month after he was carried off early in the first half. The striker appeared to twist his ankle when it became caught in the Villa Park surface and there was a lengthy delay while he received treatment, but Hernandez was unable to continue and was replaced by Antonio Valencia. Hernandez could miss six games before the new year as a result. A first United goal from Phil Jones after 20 minutes enabled the Red Devils to consolidate second place in the Premier League. United manager Sir Alex Ferguson said of Hernandez's injury: "We think it's torn ankle ligaments unfortunately. We're having a torrid time with injuries at the moment. "It could be three to four weeks." United remain five points adrift of Manchester City and Ferguson was happy with his side's dominance despite missing several good chances. He said: "We missed some good chances and that can cost you. Villa don't give in and they kept pumping that ball in at the end of the game and anything can happen then. "I thought we controlled the game and there were some good performances. "We had a good rhythm to our game today and it's a good pitch to pass the ball. We always enjoy coming here. "We've won 1-0 away again and the one good thing is we've increased our concentration away from home." Villa manager Alex McLeish confirmed winger Charles N'Zogbia is to be fined after leaving him out of his matchday squad for a breach of club rules. He said: "N'Zogbia broke a club rule. He never turned up for treatment when he was supposed to. He has to take it on the chin. "When it comes to something like that, we have to respect the rules. He has been disciplined. There will be an internal fine." In addition, Villa midfielder Jermaine Jenas and goalkeeper Shay Given face spells out of action after being stretchered off. McLeish said: "With Jenas, it is his Achilles. It is a 24-hour job, it might even be Monday before we are able to scan it. "With Shay, we are hoping it is just cramp. It might be a grade one hamstring. If it is a hamstring it can be three to four weeks. Hamstrings are never a few days but hopefully it is not too serious. "The injuries put more pressure on the squad." Villa were booed off after their first-half performance but McLeish was satisfied with the second-half showing. He said: "In the second half we were better than in the first half. When United scored their goal, it seemed to make us a bit nervous. "The fans did not like the first-half performance. I was not keen on it myself but we were a lot better in the second half. "Emile Heskey had a good chance at the back post and could have played Darren Bent in instead of trying for a wonder goal."
