Manchester United\'s 4-3 victory over Newcastle United opened a seven-point gap at the top of the Premier League table on Wednesday, but the news was not all positive for Alex Ferguson and his team. The veteran manager revealed after the game that Wayne Rooney has a knee ligament injury that will sideline him for up to three weeks, having already ruled him out of an amazing game that saw Newcastle take the lead on three occasions, only to lose to Javier Hernandez\'s 90th-minute winning goal. Ferguson, too, may yet suffer repercussions in the wake of the contest. He marched onto the field before the second half kicked off and remonstrated with the referee over the decision to award the visitors a second goal after 28 minutes. The referee over-ruled his assistant, who had initially flagged to disallow the goal because Newcastle forward Papiss Cisse was in an offside position when Danny Simpson crossed for Jonny Evans to put through his own goal. Patrice Evra scored a second equaliser for the home side, with Cisse handing Newcastle the lead for a third time, which was cancelled out by Robin van Persie before Hernandez settled the extraordinary affair. The last three seasons have seen the team leading the table at Christmas go on to win the title and United\'s seven-point advantage looks commanding, despite their defence continuing to struggle so badly. \"You have to be concerned, of course,\" said Ferguson of his club\'s defensive record. \"It\'s only the courage of the team that has got us out of it again. Some of the football in the second half was phenomenal in these conditions - really great. \"The statement was the performance, never mind where we are at this moment in time. That was a championship performance. \"It\'s a great quality to have and once again, they have proved their courage. They never gave in. Down three times and eventually they deserved to win game.\" Rooney injury blow Ferguson also has a number of injury concerns to contend with, as he prepares for Saturday\'s home meeting with West Bromwich Albion, topped by Rooney, who hurt himself when he volleyed a ball late in training on Christmas Day. \"Wayne has felt the ligament in the back of his knee in training - probably out for two or three weeks,\" said the Scot. \"It\'s unfortunate because after his performance on Sunday (in a 1-1 draw at Swansea City), I thought he would be brilliant today (Wednesday). He was desperate to play.\" Newcastle manager Alan Pardew was left to bemoan his team\'s own poor defensive performance. The visitors came within inches of recording their first away victory of the season though, with Sammy Ameobi hitting the woodwork with five minutes left and the score tied at 3-3.