Virgil van Dijk was withdrawn while Liverpool were 2-0 down at half-time at Brentford on Monday - with fears it could have been due to an injury.
It was a shambolic first-half showing from the Reds, which saw them concede from an Ibrahima Konate own goal and then Yoane Wissa's strike for the Bees.
Klopp was not impressed with the first 45 minutes, and made a trio of substitutions, including taking off 31-year-old captain Van Dijk.