"The centre-back sustained the issue during Saturday's 2-1 victory over Crystal Palace at Selhurst Park".
Liverpool's preparations have also been dealt a huge blow after a thigh injury ruled out Joel Matip for the rest of the season.
It's thought the surgery will end Matip's involvement in the 2017/18 season.
"Getting the news was, of course, absolutely bad, especially with the background - Joe (Gomez) is already out, Ragnar (Klavan) is not fit, Emre (Can) is struggling. He was injured the last two weeks", said Guardiola. "That left us a little bit concerned". Klopp had been alternating between Matip and Lovren as he figures out the best partner for £75m man Virgil van Dijk, but Matip's injury has put paid to that, with Lovren now Van Dijk's automatic partner for the rest of the campaign.
The 29-year-old has only made one Premier League this season due to numerous injuries and recently hoped his fitness issues were behind him as he targeted a place in England's World Cup squad. It is absolutely not the time to bring any rush into the situation.
Klopp will likely provide further updates on Matip when he sits down for his pre-match press conference on Tuesday afternoon.