Portugal have been dealt a blow ahead of the World Cup with forward Diogo Jota ruled out of the tournament in Qatar due to a calf injury, Liverpool manager Juergen Klopp said on Tuesday.

Jota, 25, was taken off on a stretcher deep into stoppage time during Liverpool's 1-0 Premier League win against champions Manchester City at the weekend.

"Really not good news, yes he will miss the World Cup. Pretty serious injury in the calf muscle and now the process starts. That's it pretty much," said Klopp, adding that Jota would not require surgery.

"All the rest will now follow in the next few days. Very sad news for the boy, for us as well and for Portugal... I don't want to put a time on it (his return). It will be a long time."

Jota, who has scored 10 times in 29 appearances for Portugal, had only regained full fitness after missing the opening few weeks of the season due to a hamstring problem.

He becomes the second Liverpool player to miss out on the World Cup after Colombian Luis Diaz was sidelined due to a knee injury.

Asked how Jota had taken the news, Klopp said: "He's surprisingly okay so far, a smart boy and he knew it when we carried him off. At that moment he knew it."

Klopp was sent to the stands following a heated altercation with the assistant referee during the win against City but the German expects to be in the dugout at home to West Ham United on Wednesday.

"I think I will be there tomorrow because nothing happened yet. I don't think something will happen tomorrow a few hours before the game," he said.

Klopp's outburst attracted criticism from Ref Support UK, a charity that offers support to referees in grassroots football where abuse is common. City boss Pep Guardiola's behaviour was also called into question.

"I still think I should have dealt differently with the situation which I usually do," added Klopp.

"The whole game led to that a little bit. It was a very, very intense game with a lot of decisions we didn't understand on both sides... I'm not happy with my reaction but that's the way it was and everybody saw it."

Liverpool are eighth in the league standings with 13 points from nine games, two points ahead of 12th-placed West Ham.