Oxlade-Chamberlain spent some time receiving treatment on the sidelines after sustaining an injury while challenging Aleksandar Kolarov.
The Liverpool man was forced off during the first half and was replaced with Gini Wijnaldum with just 19 minutes on the clock.
The injury looked serious with the England international shrieking in pain almost immediately as he grabbed his knee.
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Klopp confirmed at the end of the match that the injury looks 'bad', but will require a scan.
The manager told BT Sport post-match: “Oxlade-Chamberlain, it's probably a really bad injury.
“If we can say that already before the scan, that's never good news so that means for us it's a massive blow, of course.
“We have still a few very important games to go and the squad doesn't get bigger in the moment, so we obviously need to be creative in the next few games.”
The Echo's James Pearce shed light on Liverpool's initial view of the injury, fearing he could miss the World Cup.
Oxlade-Chamberlain's injury the sour note for #LFC tonight. Initial fears are that he will miss the rest of the season and the World Cup.
It appears Oxlade-Chamberlain could be ruled out for the rest of the season if initial worries of the midfielder doing his anterior cruciate ligament (ACL) are realised.
The former Arsenal man will be hoping the scans reveal a different picture as he is set to be included in England's squad for this summer's World Cup.