Watford forward Mauro Zarate faces a lengthy spell on the sidelines after suffering a cruciate ligament injury in Saturday's 1-1 draw with West Ham.
The 29-year-old was taken off on a stretcher in his third appearance since joining from Fiorentina in January.
In an Instagram post, Zarate said scans revealed an "anterior cruciate ligament rupture plus an injury grade one of [the] medial collateral ligament".
The typical recovery period for a cruciate ligament injury is six months.
However, it can be longer if surgery is required.
"Thank you everyone for all the messages in this horrible moment," former West Ham and QPR striker Zarate added.