Devin Toner has been left out of Ireland's 31-man squad for the Rugby World Cup in Japan.
The 33-year-old Leinster lock has made 60 appearances under head coach Joe Schmidt, more than any other player during the Kiwi's six-year tenure.
Munster's South Africa-born Jean Kleyn has been given the nod ahead of Toner, with Ulster back Will Addison also not included in the final selection.
Schmidt was not expected to name his squad until Sunday.
The side play their final warm-up game against Wales in Dublin on Saturday, with their opening World Cup Pool A game coming against Scotland on 22 September.
Three Ulster players, captain Rory Best, second row Iain Henderson and wing Jacob Stockdale, are in the squad while missing out along with Addison are Jordi Murphy and new signing Jack McGrath.
Kleyn only qualified for Ireland on residency two days before his Test debut, the 29-10 victory over Italy on August 10, but the 26-year-old edged out Toner, who has started 50 of Schmidt's 67 Test matches in charge.
"I've coached Dev for 10 years, he's not just our line-out champion but he's such a good player, and he's an absolutely quality person. That was an incredibly tough conversation yesterday," said Schmidt.
"Jean Kleyn - we probably don't have a specialist tight-head second row as such and I think we're looking for that balance. Tadhg Beirne gives us that versatility and he's teamed up with Kleyn really well at Munster this year.
"He gives you the threat over the ball like a 6 or 7 would and can play in the back row. We have James Ryan who's made an immediate impression.
"Iain Henderson has promised so much and performed incredibly well for us at times. We're going to need him to put his best foot forward so it was a very tight decision around Dev as well."
Connacht scrum-half Kieran Marmion has been left out with Schmidt going with Luke McGrath as Conor Murray's back-up, while Chris Farrell also gets the nod as a versatile back ahead of Addison.
"It was a difficult thing right from the start to have the 45 that we had," added Schmidt.
"We went down to 40 players and to go from 40 down to 31 was really difficult, but we had a process whereby we looked back through every training, looked through the games.
"There were some guys who obviously had more experience and probably had more credit in the bank and were more established.
"And there were other guys who were trying to force their way into the group and trying to get a balance of current form versus previous performance. It's always a very, very difficult conundrum to try to solve."