Alexander-Arnold, 20, faced plenty of criticism in the wake of the trip to Old Trafford last March as he was tormented by Marcus Rashford, who scored twice in the opening 25 minutes of United's 2-1 win.
Ahead of another meeting with Liverpool's rivals, Alexander-Arnold said he still calls upon that encounter to encourage his continued development.
"I still use that game as a learning point," the England international told reporters.
"That is probably the best thing to do – look back on the harder games you've had, the tougher games, learn what I didn't do well and what I could have done better.
"The Manchester United game was definitely one of those games but rather than let it get me down, or put me down and think that maybe I am not good enough at this level, it was important to use it as a positive and see it as a learning step to improve.
"I needed to use it as motivation to make sure something like that doesn't happen again and to prove that you are better than you showed on that day."