Lamine Yamal, the second youngest player ever in the UCL.

FC Barcelona's new rising star made his Champions League debut for Barcelona in the match against Royal Antwerp when he replaced Joao Felix after 68 minutes, making him the second youngest player in history to make his Champions League debut.

Youngest players to reach debut in UEFA Champions League: 
Youssoufa Moukoko (16 years 18 days)
Lamine Yamal (16 years 68 days)
Céléstine Babayaro (16 years 86 days)
Rayan Cherki (16 years 102 days)
Alen Halilović (16 years 128 days)

Yamal must settle for second place among all players in the Champions League, but he can console himself with the fact that he set a record on Tuesday night, becoming the youngest Barcelona player to debut in the Champions League. 

Youngest Barcelona debutants in the Champions League:
Lamine Yamal (16 years 68 days)
Ansu Fati (16 years 321 days old)
Bojan Krkic (17+)
Lionel Messi (17+) 

Lamine Yamal can become the youngest scorer in Champions League history. To achieve this, he needs to score in this year's Champions League, which would surpass his former teammate Ansu Fati's record.

Youngest goal scorers in Champions League: 
17 years 40 days: Ansu Fati 
17 years 149 days: Antonio Nusa 
17 years 194 days: Peter Ofori-Quaye

Yamal is certainly a huge talent, and he has a bright future ahead of him. Xavi seems to have a lot of confidence in his young forward, so he should be able to produce goals and assists this season.