 The deal was a cooperation between New York Red Bulls and Austrian club Red Bull Salzburg, with Nielsen scheduled to ultimately join Red Bull Salzburg on 1 January 2011, according to Salzburg official Christoph Freund.As the Austrian transfer window was already closed, a direct buy was not possible for Salzburg, with Nielsen instead moving to New York Red Bulls as the US transfer window was open until April 15.Salzburg purchased Nielsen in 2010-11 and loaned him back to New York for the 2011 MLS season.