Is it too late to get a decent seat?

I arrived back from a two month holiday in the U.S. and while there I had completely forgotten about the upcoming Manchester United match on the 13th of July. Up here in Surin I have been unable to get any feedback about buying a ticket at this late date. I imagine the match is sold out but is there a chance that some tickets are still available? Would it be worth the time and effort to show up at the Stadium and hope there are some "scalpers" plying their trade? I am P.O.ed at my own stupidity for forgetting the match in the first place.