MANCHESTER UNITED legend Gary Neville has pleaded with the club not to sell Wayne Rooney to Chelsea. Rooney's future at Old Trafford has been one of the predominant themes of the transfer window to date, and he raised the spectre of a move to Stamford Bridge after asking to train with the reserve team today. The 27-year-old, who was included in Roy Hodgson's England squad for the friendly next Wednesday against Scotland, has yet to feature for United during pre-season due to injury. And Neville said it's unthinkable for United to sell Rooney, who could still play an instrumental role in their hunt for a 21st title. "Manchester United cannot sell Wayne Rooney to Chelsea Football Club - unless they bring in a major, major signing like Gareth Bale or Cristiano Ronaldo," Neville told Sky Sports. "You have absolute gold in Rooney, someone who is proven over six, seven, eight years; who delivers season in, season out; and is one of the top goals and assists man in the league consistently - even last season when he wasn't at his strongest. "He will work his backside off and never drop his level in training and the importance of Rooney [is huge]; he is a vital player, a champion player and someone that wins you the league. "He is the guy who in the middle of October when you are four points behind in the league, going to Chelsea and have Arsenal the week after, sits in front of his midfield two, works his backside off, gets up the pitch, gets back, sets up goals and digs in. "Don't underestimate the value of Rooney to Manchester United's success over the last eight years and the way he is liked amongst his team-mates."