Jota was carried off the pitch on a stretcher late in Liverpool's 1-0 Premier League win over Manchester City at Anfield on Sunday.
And Reds manager Jurgen Klopp confirmed that the injury will mean Jots is out for "months" and results in the 25-year-old missing the World Cup that kicks off in the Middle East on November 20.
“It’s really not good news about Diogo. Yes, he will miss the World Cup,” said Klopp, before Liverpool's Premier League game at home to West Ham United on Wednesday.
“[It’s a] pretty serious injury in the calf muscle and now the recovery process starts. That’s it pretty much.
“That is the first diagnosis, which was pretty clear, and all the rest will now follow in the next few days. It is very sad news for the boy, and for us as well as for Portugal.
“[It will have a] big impact. So, now we can say that because he will not be in for a long time; we talk about months.
Liverpool 1 Man City 0: player ratings
“So, we will see. I don’t want to put now a number on it because I always hope in the middle of the rehab there is a very positive development and we can cut days off the rehab phase, but it will be long.
“He's surprisingly OK so far. He's an incredibly smart boy. I think he knew it when we carried him off the pitch.”
“We passed each other after the game and he explained pretty much what had happened. I think he knew it was a serious one and could be pretty impactful for his World Cup dreams.”
Jota was an expected starter for Portugal in a World Cup group that includes Ghana, South Korea and Uruguay. Their campaign begins against the African nation on November 24.
Portugal also lost winger Pedro Neto last week due to an ankle injury on club duty, for Wolves, that requires surgery.