A former Spanish youth international, capped at every level up to Under-21, Adan progressed through the academy of La Liga giants Real Madrid.
After playing a number of games for the reserve teams of Los Blancos, he graduated into the first-team in 2010, and was made starting stopper by head coach Jose Mourinho after a number of high profile mistakes by Iker Casillas.
He ended up making 18 appearances in all for Madrid, leaving the club in 2013 to join Cagliari, although he only spent one season in Italy before returning to his homeland, and signing with La Liga’s Real Betis.
They were relegated at the end of that season, but Adan played a central role in their fight to stay in the top flight, and he has played all 30 games as Betis sit atop the table in the Segunda Division.
He has conceded just 27 goals in 30 games, keeping 14 clean sheets, and his form has reportedly piqued the interest of Everton and Sunderland.
The Premier League clubs are looking to revitalise their goalkeeping departments in the summer - with Costel Pantilimon and Tim Howard struggling this term - and Adan seems to have been earmarked as one of their successors.