The Netherlands international has been heavily linked with a move to Old Trafford following Louis van Gaal's appointment, with the club keen to add another left-sided player to the squad following Patrice Evra's departure and doubts over the fitness of Luke Shaw.
And now Witschge has revealed that Blind is not taking part in training with the rest of the Ajax squad and suspects that the 24-year-old is keeping himself protected so as not to obstruct any transfer away from Amsterdam.
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According to Ajax, Blind took part in sprint drills on Thursday – having recently joined the squad ahead of schedule after his exploits at the World Cup – with Nick Viergever the only player to train away from the main group.
Blind excelled in Brazil under Van Gaal, notably producing two assists in Oranje's opening-game demolition of Spain, and has previously acknowledged speculation linking him with a move to United.
"All the attention is a very big thing now," he said in June, "but I try not to think about it too much and will keep my feet on the ground.
"The link with Manchester United is easily made because Robin [van Persie] is playing there and Van Gaal takes over next season."
Blind, whose current deal at the Amsterdam Arena expires in June 2016, has attracted interest from several clubs, according to his agent, Rob Jansen, including the likes of Barcelona.