After facing Romania and Tonga the Irish take on South Africa and Scotland in the fixtures that will likely decide the outcome of the group and Farrell has chosen to keep World Player of the Year Van der Flier in reserve for the challenges ahead.
Instead, Peter O'Mahony has been named at openside flanker and Tadhg Beirne at blindside in a team bristling with experience, with some added youthful exuberance in the shape of 22-year-old Leinster lock Joe McCarthy.
"There's no mix and match really now - we've got a squad of 33 that we totally believe in," Farrell told reporters.
"Whatever team we put out will be a good side, no matter what, it will be a team that's threatening and a determined one at that," he added.
Forwards coach Paul O'Connell, who won 108 caps and a Grand Slam with Ireland during a glittering career, said the current Irish squad had an athleticism and intelligence beyond what he and his peers displayed.
"Physically a lot of us were incredibly committed but these guys? There's some serious athletes in the team, particularly around the forward pack," he told reporters.
"We've players that are able to figure things out really quickly... that's the biggest thing I've found since I came back into the Irish set-up two years ago. The smarts of the players is a real strength of theirs."
Playing in his final World Cup, Sexton is named at out-half with winger Keith Earls, who scored a try against England on his 100th cap in a recent World Cup warm-up game, also included in the starting lineup.
Jamison Gibson-Park takes scrum-half duties with Bundi Aki and Garry Ringrose in the centre positions, while James Lowe is set to be deployed on the opposite wing to Earls with Hugo Keenan in at fullback.
Ireland team:
15. Hugo Keenan, 14. Keith Earls, 13. Garry Ringrose, 12. Bundee Aki, 11. James Lowe, 10. Johnny Sexton (captain), 9. Jamison Gibson-Park; 8. Caelan Doris, 7. Peter O'Mahony, 6. Tadhg Beirne, 5. James Ryan, 4. Joe McCarthy, 3. Tadhg Furlong, 2. Rob Herring, 1. Andrew Porter
