Manchester United trailed three times before a last-gasp goal from Javier Hernandez sealed a rip-roaring 4-3 victory over Newcastle United that opened a seven-point lead at the top of the Premier League on Wednesday. Manchester City were undone by former winger Adam Johnson as he scored the only goal in a 1-0 win for Sunderland which left the champions second in the table, four points ahead of Chelsea who beat Norwich City 1-0 thanks to a 20-metre strike from Juan Mata. Tottenham Hotspur moved up to fourth after Gareth Bale grabbed his first Premier League hat-trick in a 4-0 rout at Aston Villa who were also thrashed 8-0 at Chelsea on Sunday. As they have done so many times this season Manchester United fell behind early on but even without the injured Wayne Rooney they offered another dazzling display of firepower. James Perch delighted the Newcastle fans with a fourth-minute opener at Old Trafford. Jonny Evans levelled in the 25th minute before the Manchester United defender put through his own net four minutes later as the visitors went back in front in controversial fashion. Patrice Evra equalised for the home team but Papiss Cisse then gave Newcastle a 3-2 lead….