West Ham United are reportedly struggling to complete a deal for New York Red Bulls centre-back Aaron Long because of work permit issues.
The 26-year-old is a regular for the United States national team and is the reigning MLS Defender of the Year.
United are prepared to trigger his £4m release clause, but Sky Sports News claims that they have various other hurdles to overcome.
French trio Marseille, Rennes and Lyon are also rumoured to be in the running to sign Long, as are Italian side Fiorentina.
West Ham have already brought in four players this summer, including striker Sebastien Haller from Eintracht Frankfurt for a club-record fee.
