Tommy Oar's proposed move to Athletic Bilbao fell through after the club deemed that the winger did not possess significant Basque heritage.
The Australian thought he could be eligible to play for the club thanks to his paternal grandparents being from the region, but Athletic only allow players born in the Basque Country or those who have come through the junior ranks to represent the club.
Despite the heritage, the 25-time capped Australian international, was told he was not eligible to represent the club, after leaving FC Utrecht when his contract expired in the summer.
"It was obviously disappointing that it didn't work out," Oar told SBS.
"For a few weeks there I was hopeful that it would happen but unfortunately it didn't go ahead because of the club's policy.
"It would have been the perfect step ... they are a fantastic, ambitious club but it wasn't to be."
It is not the first time the Spanish Super Cup winners have rejected a player as he was not able to to prove his Basque credentials.
Diego Forlan has previously stated he would have loved to play for the club, as the Uruguayan's grandmother was Basque, but he did match los leones' playing criteria.