13岁零343天，阿森纳小将成为青年欧冠历史上最年轻出场球员（阿森纳13岁343天小将创青年欧冠最年轻出场纪录）

Considering UEFA Youth League Records

I want to make sure I provide a clear news brief template with placeholders, but I should avoid fabricating any facts. I could ask for the player’s name and match details. It’s important to include background on UEFA Youth League age rules, noting it’s a U19 competition with specific criteria for overage players. For instance, Moukoko made history at 14 years 9 months. I'm a bit unsure about the previous record holder, so I should state it as new per the user’s info.