Two weeks later and it was cruelly taken from him in mysterious circumstances.

The second division Spanish club had already unveiled the former Sydney FC player as a new signing at a press conference, handed him his new jersey and presented him to the fans before cruelly withdrawing their offer following the formality of a medical examination.

The club did not reveal the findings of the medical examination or further explain their decision to not follow through on the signing of Naumoff despite unveiling the player to the public days before.

"After the first medical examination required other surveys and explorations that have finally led the club to take this tough decision," a club statement said.

Medical examinations are a formal requirement for player signings and rarely do they form the basis of a late get-out for clubs.

Naumoff had no known injuries while at Sydney FC last season and played in their final match of the season, a 2-2 draw with Shandong Luneng in the Asian Champions League knock-out stages.

Sydney FC sources informed Fairfax Media that Naumoff had no injury concerns while with the club and were shocked to hear news of Numancia discovering any fitness problems.

The 21-year-old has no record of serious injury during his A-League career.

Naumoff previously signed with Numancia as a free agent at the end of his deal with Sydney FC, though the Spanish team did have to pay a small training compensation fee in the vicinity of $100,000.