Six out of the nine are backs, with Gavin Duffy playing at full-back for the first time.
But Trimble, the fourth most experienced in the starting XV with 14 caps, believes a combination of youth and will can help the team defeat Argentina away from home for the first time.
He said: "Even though there is a lot of inexperience in this team, there are a lot of guys who are extremely keen and a lot of young fellas like myself and we all have a big opportunity to play a very important game as Saturday's is," said the 22-year-old.
But the end goal for the 30 players in the Irish squad is to be one of the party who travel to France for the World Cup this autumn and, with coach O'Sullivan confirming half of the places are still up for grabs, Saturday's match is the perfect opportunity for them to prove their credentials.
Trimble, for one, has not looked back since he initially broke into the Ulster midfield in 2004 and sees the tour to Argentina as his chance to show he can cut it against powerful opposition.
"We are very excited to get stuck into this game, because there are World Cup places at stake," he said. "Everybody here wants to be at the World Cup so everybody is looking to impress Eddie."
And Trimble expects "a very physical game" against Marcelo Loffreda's side.
"The physical strength of the Argentine pack is great, so I think it will be vital to beat them," he said.
"When we meet their pack for the first time we'll have to do so with determination and be very in their face to see how they manage that."
The first of the two Argentina Tests will be played on Saturday at the Brigadier Estanislao Lopez stadium, the home of football team Colon.
The teams will meet again a week later at the Jose Amalfitani stadium in Buenos Aires.