England – Kepu Tuipulotu
The 19-year-old hooker has already made his Bath debut in both Europe and the Premiership.
Tuipulotu is an abrasive ball carrier and showed all that skill against Ireland Under-18s in 2023 when he bounced off multiple defenders, external to score a superb solo try.
The son of former Tonga and Dragons centre Sione, and brother of current Wales women’s international Sisilia, he is also eligible for Wales.
Could strong performances see him fast-tracked into the England senior set-up to fend off possible Welsh interest?
Ireland – Eanna McCarthy
The Connacht academy player has been named Ireland captain even though Thursday’s match against England will be his under-20 debut.
Ireland have produced a number of high-quality back rowers in recent years and the all-action McCarthy will hope he is another one off the conveyor belt.
With seven returning players from last season, being handed the captaincy shows how highly McCarthy is rated in the Irish system.
Wales – Tom Bowen
The 19-year-old has started three games for Cardiff on the left wing in this year’s Challenge Cup, scoring on his debut against South African side Cheetahs.
Bowen has a lethal left-foot step and an exceptional turn of pace, which has been evident already in the professional game.
Scotland – Jack Brown
Full-back Jack Brown featured for Scotland A in their narrow victory over Chile and trained with Gregor Townsend’s senior team in the lead-up to their win against Australia in November.
The 19-year-old has a strong running game and started against Ireland in last year’s championship.
He will hope senior appearances for Edinburgh will come his way if he steps up this campaign.
France – Simeli Daunivucu
Centre Daunivucu made his La Rochelle debut last season and has featured 11 times for Ronan O’Gara’s side.
The 19-year-old is a strong, skilful player and son of former Fiji scrum-half Jone Daunivucu.
He was selected for France’s tour of Argentina in the summer but did not pick up his first senior cap.
Italy – Giacomo Milano
Milano featured in all of Italy’s under-20 games last year, playing at lock and in the back row.
The versatile forward went on to make his United Rugby Championship debut for Zebre in October against South African side Lions, before starting twice in the Challenge Cup.
At 6ft 4in tall and weighing more than 17 stone, the 19-year-old is destructive with ball in hand and packs a punch in defence.