Aiden McGeady, Sean St Ledger, Joey O'Brien and Paddy Madden have withdrawn from the Republic of Ireland squad for their forthcoming World Cup qualifiers.
Giovanni Trapattoni's side face Sweden at the Aviva Stadium on 6 September and Austria in Vienna on 10 September.
The quartet have all pulled out because of knee injuries.
QPR defender Richard Dunne is in the final 23-man squad named by Trapattoni on Friday while Hull's David Meyler is placed on the standby list.
Earlier this week, Derby midfielder Jeff Hendrick was forced to pull out of the panel.
Hendrick sustained an ankle injury in Derby's win over Yeovil on Saturday.
Hendrick made his Republic of Ireland debut in the friendly against Poland in February and he has accumulated three more caps since then.
His first Republic appearance saw him setting up a goal for Wes Hoolahan with a perfectly weighted pass and manager Trapattoni has made it clear than he rates Hendrick highly.
Trapattoni's team lie fourth in Group C but only trail Austria and Sweden on goal difference, with second place likely to be enough for a play-off spot.
Republic of Ireland squad: Forde, Westwood, Randolph, O'Shea, Wilson, Coleman, Kelly, O'Dea, Clark, Dunne, McShane, Whelan, McCarthy, Green, Pilkington, McClean, Brady, Hoolahan, Long, Keane, Sammon, Walters, Cox.