The 26-year-old defender played for 65 minutes during the team’s opening Club World Cup match against Al Hilal in Miami, though was substituted by head coach Xabi Alonso.
Although Madrid did not lose, the team’s 1-1 draw marked the first time the Spanish giants have failed to secure a victory in a Club World Cup match.
Now, Alexander-Arnold has reflected on the frustrating result.
He said after the match: “It's a very proud moment for me, very happy to have made my debut. It's something that I think most, if not all, players dream of at some point in their life, I'm incredibly proud of the achievement.
“Of course, there's some disappointment I think. The mentality that comes with being a Madrid player is wanting and expecting to win every single game.
“But a new coach, some new players, new ideas, some positives in there to take from it, especially in the second half, and foundations being built to go and win the next game.”
Gonzalo Garcia scored the opening goal for Madrid in the 34th minute, though Ruben Neves equalized with a penalty seven minutes later.
Then during injury time, Federico Valverde missed a spot kick, and the game ended with a 1-1 draw.
Following the disappointing result, Alonso admitted Madrid was “lacking in several eras”, and the team “couldn’t find balance”.
He said: “The second half was considerably better than the first. We were lacking in several areas in the first period, both with and without the ball. We were losing the ball too quickly, we couldn't find a balance.
“They're things we have talked about but we took a while to get to grips with them. I'm pleased with the reaction at half-time.
“We managed to give a new look to the game, change the pace a bit and find more guys to bring the right rhythm and control to the play. That helped us get in good positions around the opposition box, adjust our press, and we spent more time near their area.
“This is a process. Everything takes time. The first half wasn't very good but we have to take the positives and look at how we can learn from the negatives.”
