Liverpool boss Jurgen Klopp has said winger Alex Oxlade-Chamberlain sustained a "serious" hamstring injury during pre-season.
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.