This list is taken from Transfermarkt which counts all competitive competitions that Liverpool play in.
5. James Norris - 16 years, 8 months and 13 days
Fullback James Norris debuted for Liverpool in 2019 as a 16-year-old when the Liverpool U21s were forced to play a Carabao Cup semifinal match against Aston Villa as the senior side was busy in Qatar with the FIFA Club World Cup. The Reds went on to lose the game 5-0, but Norris came on in the 82nd minute, replacing Ki-Jana Hoever.
Norris is still at Liverpool but has spent this season on loan at Tranmere Rovers in League Two. The now 21-year-old has dealt with injuries this season and, despite the historic debut, is unlikely to have a long-term future at Liverpool.
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