Georgia's 18-year-old half-back Vasil Lobzhanidze will become the youngest player in World Cup history after being named to face Tonga.
The rugby youngster said he was counting on his more experienced teammates to help him get over his nerves before the match.
"Yes I am very happy to be the youngest player in the history of the Rugby World Cup," Lobzhanidze said after being named in the team.
"I am a little bit nervous, but we have a team with a lot of experience so this makes me less nervous for when I get out on the field."
He said his family knew about the appearance and would be watching.
Lobzhanidze will break the record held by American Thretton Palamo who was 19 years and eight days old when he played South Africa at the 2007 World Cup.
Lobzhanidze barely remembers the last World Cup in 2011 and only took up rugby union sevens years ago.
"Just a few years ago, I would not have imagined that I would play for the Georgian national team, let alone at a World Cup," he said before coach Milton Haig named the team to play Tonga in their opening Pool C game in Gloucester.
Lobzhanidze was still at school for the last World Cup in New Zealand.
"I was very young, so I almost don't remember the last World Cup.
"I started playing rugby in Tbilisi when I was 11-years-old in one of the clubs, Armazi Tbilisi which is a club that plays in the top division in Georgia, and that is where I still play today."
Haig said that Lobzhanidze was in the squad "because he is one of the top three scrum-halves in Georgia and he's our number one number nine."
"Although he is only 18, he plays and makes decisions like a 25 or 26-year-old, and he makes good decisions under pressure.
New Zealander Haig has set a target of two wins, which should ensure they qualify for the 2019 World Cup.
Tonga and Namibia will be the main targets. The group also includes champions New Zealand and 2007 semi-finalists Argentina.
Tonga beat Georgia 23-9 last year.
Tonga's starting XV shows six changes from Tonga's most recent test, a 21-16 win over Romania in Bucharest on 5 September.
If wing Fetu'u Vainikolo scores he will become Tonga's outright leading test-match try scorer. He is currently tied on 14 with Josh Taumalolo.
"Playing them last year, we got the upper hand but, coming to the World Cup, we have to prepare to attack them up front and execute how we want to play the game by taking forward our strengths as well," said Tonga coach Mana 'Otai.
"It is similar to a boxing match. We have got to try to take their strengths out and apply our own," he added.