Dublin - Hooker Jerry Flannery, wing Luke Fitzgerald, scrumhalf Tomas O'Leary and lock Leo Cullen missed out on Ireland's 34-man squad for next month's internationals but could be recalled if their fitness improves.
Ireland will host South Africa, Samoa, New Zealand and Argentina on successive weekends from November 6.
"We felt it was important to have at least 30 fit players to choose from in terms of setting the foundations for November and it was better for those who picked up knocks to be assessed back in the provinces and when they have the all clear, to come back into the squad ... over the next couple of weeks," coach Declan Kidney said on Tuesday.
"We need everybody in a position to be able to contribute in training.
"There are a lot of players who are unlucky not to make this squad, but the door will remain open to them also during November to join up with the panel."
Fullback Geordan Murphy was left out, while Keith Earls, Rory Best, Stephen Ferris, Denis Leamy, Sean O'Brien and Donnacha Ryan were all recalled after missing the team's June tour to New Zealand and Australia.
Ireland plays the world champion Springboks on November 6 in its first game at the rebuilt Lansdowne Road stadium.
"There will be a lot of talk about the new stadium and also about the Rugby World Cup, but the responsibility for the squad and management will be firmly to concentrate on the first game and then take each week as it comes," Kidney said.
Forwards: Rory Best, Tony Buckley, Tom Court, Sean Cronin, Stephen Ferris, John Hayes, Cian Healy, Jamie Heaslip, Marcus Horan, Denis Leamy, John Muldoon, Donncha O'Callaghan, Sean O'Brien, Mick O'Driscoll, Mike Ross, Donnacha Ryan, Devin Toner, Damien Varley, David Wallace.
Backs: Isaac Boss, Tommy Bowe, Gordon D'Arcy, Gavin Duffy, Keith Earls, Shane Horgan, Rob Kearney, Johne Murphy, Ronan O'Gara, Brian O'Driscoll, Eoin Reddan, Jonathan Sexton, Peter Stringer, Andrew Trimble, Paddy Wallace.