Oxlade-Chamberlain injured his hamstring in Liverpool's pre-season win over Crystal Palace in Singapore
Liverpool boss Jurgen Klopp has said winger Alex Oxlade-Chamberlain sustained a "serious" hamstring injury during pre-season.
The 28-year-old picked up the injury during Liverpool's win over Crystal Palace in Singapore on 15 July.
Klopp also said goalkeeper Caoimhin Kelleher will not return to fitness for another "two, three weeks".
"With Oxlade it will take longer. It's a serious hamstring injury and it will take longer," said Klopp.
"But it's a hamstring, and we all hate this word, we hate the injury but anyway it happens from time to time and now Ox was the one."
Oxlade-Chamerlain has suffered several injury setbacks since joining Liverpool from Arsenal in 2017, including a knee problem that kept him out for a year from April 2018.
Kelleher also remains sidelined having picked up an unspecified injury while on international duty with the Republic of Ireland in June.
"Yeah, Caoimhin felt something after the international game and everybody, the medical department there, told him it's fine and will be good after holiday," Klopp said.
"He came back and first training [session] felt it again. We checked it and it was not good so I think he will be another two, three weeks and then he should be fine."
Liverpool face Manchester City in the Community Shield at King Power Stadium on Saturday (17:00 BST).
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Source: bbc.com