Trent Alexander-Arnold cut an unhappy figure after being subbed against Brentford, Arne Slot says he "understands" why.
📺 Subscribe to This Is Anfield on YouTube to watch every #LFC press conference in full, for free: https://goo.gl/Lh7zfK
📱 Download the #ThisIsAnfield App for #Liverpool FC news, opinion, video and analysis: http://www.thisisanfield.com/app/