Valencia defender Alexis has been ruled out for around four months with a knee injury.
The 22-year-old was stretchered off just four minutes into Valencia's 2-0 victory at Real Mallorca on Saturday after landing awkwardly.
A series of tests have now confirmed that he has severe ligament damage and will not be available again this year.
Initial predictions suggest Alexis could return in February or March 2008.
It is a major blow for the centre-back, who joined Valencia over the summer and has made four appearances so far this season.
He had been hoping to prove himself to new boss Ronald Koeman, who takes charge of his first game when Valencia face Rosenborg in the UEFA Champions League on Tuesday.