Reports claim that United have had a £20.5million bid turned down by Spurs this week and now its a race against time for the deal to be finalised before the window closes at midnight on Monday.
Ferguson has suggested the champions are unwilling to match Spurs' valuation, believed to be closer to £30million, for the 27-year-old and now the whole deal appears to be hanging in the balance.
The United boss revealed: "I'm less optimistic, so we'll carry on. I've no idea what's going on.
"It's very hard to get communication with some people in life."
Berbatov's agent Emil Danchev is expected to hold emergency talks with Spurs officials on Friday, as he tried to resolve the stand off one way or another.




