Manchester United will not let Juan Mata join Atletico Madrid unless Koke comes the other way, according to reports.
Mata has been linked with a move away from Old Trafford this season, with Diego Simeone apparently identifying him as a transfer target.
However, The Metro claims that United want 22-year-old midfielder Koke from Atletico in exchange for the former Chelsea playmaker.
Mata has struggled to establish himself in Louis van Gaal's first team this season.