The Primera Division outfit have announced that the Italy international, who underwent surgery on Friday, must go under the knife again at the tail end of the summer
The Italy international tore his anterior cruciate ligament for the second time in less than six months during a training session on April 13.
It was initially thought that Rossi, who went under the knife in the United States on Friday, would be sidelined for a further six months, but it has now been confirmed that he will not play again this year.
"With the objective that Giuseppe Rossi returns to his best physical condition, the most secure procedure consists of two separate operations," a statement on Villarreal's official website read.
As a result, Rossi will be back on the operating table in four months. The former Manchester United striker had originally been hoping to represent his country in Euro 2012 and had also been heavily linked with a return to Serie A before he suffered his injury setback earlier in April.