England striker Wayne Rooney has been left out of Manchester United's squad due to a shoulder injury ahead of United's FA Community Shield match against Wigan ( live, FOX Soccer, Sunday, 8:45 a.m. ET ) further adding speculation regarding his future at Old Trafford.

The 27-year-old, who was named by Roy Hodgson in his England squad to face Scotland next Wednesday when it was unveiled Thursday, is yet to play a competitive game during United's preseason. Rooney has struggled with shoulder and hamstring injuries this offseason. Hodgson admitted earlier in the week that he will tread carefully with the England forward's fitness when he reports for international duty early next week.

Hodgson told Sky Sports News : "My selection of him could be used as a wedge between David Moyes and myself and there won't be any wedges put between us two. We've been friends for a long time. David understands my situation fully and put simply we have four very important games coming up.

Rooney has been strongly linked with a move to Stamford Bridge after Chelsea lodged a bid for the unsettled forward. United have repeatedly insisted the striker is not for sale, but Chelsea manager Jose Mourinho insists his club has no plans to give up on his target.

"There is no time limit," said Mourinho. "We have our squad of strikers. We have identified the player as one we would look to have with us."

The interest is believed to frustrate United with the Premier League champions continuing to be adamant that they have no intention of letting Rooney go. But Mourinho believes Chelsea have acted properly in their dealings, having done all of their activity through the official channels.

He added: "We are doing things legally, making the official bid directly to the club, no interviews or comments or direct relations with the player, no contact, absolutely nothing. We have done it in an ethical way and we are going to do that until the last day. And we will see how it comes."

FOXSoccer.com's newswire services contributed to this report.