The England international does not require surgery but he is expected to miss Liverpool’s first three Premier League games of the season.
But Brendan Rodgers said that Liverpool will not rush Lallana back saying:
“Of course it was very disappointing – it’s probably going to be four to six weeks,” Rodgers said at a press conference from Soldier Field in Chicago.
“He has looked fantastic in training; it was just a very simple exercise with no pressure. The medical team are looking closely at that at the moment.
“We’re hopeful that he’ll come back fairly quickly, but there’s no rush. He’s a fantastic player, we just need to get him back fit and well because it’s a long season.”
Big blow for Lallana and Liverpool as he was expected to be a major contributor in the Reds title challenge this season.