Alex Oxlade-Chamberlain suffered a muscle injury during Liverpool's 2-0 victory against Crystal Palace on Friday that requires further assessment, Jürgen Klopp confirmed.
The No.15 was forced off with the issue during the latter stages of the first half in the win over Patrick Vieira's side in Singapore.
Offering an update post-match, Klopp told a press conference: "Of course it's very disappointing for us because Oxlade trained all the time really well since the pre-season started.
"It happened obviously with Ox in the past when it gets more intense and something can happen. Now this is just a muscle thing and that's OK.