Andy Reid has withdrawn from the Republic of Ireland's training camp in Portugal because of a hamstring injury.
The 25-year-old Sunderland midfielder, who met up with the squad in Dublin on Wednesday and trained on Thursday, was due to fly out to the Algarve with the rest of the party on Friday evening.
However, he did not train at Malahide this morning and manager Giovanni Trapattoni later revealed he would not be on the plane.
There is a doubt too over Birmingham goalkeeper Colin Doyle because of a knee problem which is being assessed by doctors.
Trapattoni is already without Shay Given, Lee Carsley, Kevin Kilbane, Darron Gibson and Joey O'Brien through injury, while John O'Shea, Robbie Keane, Richard Dunne, Aiden McGeady and Darren O'Dea will not join up with their team-mates until they return to Dublin next Thursday because of club or personal commitments.
In fact, of the 28 men initially selected, only 21 were due to fly out to Portugal, and one fewer if Doyle's problem proves significant.
However, Trapattoni, who put his players through their paces on Thursday night and again on Friday, has been happy with what he has seen so far.
He said: "The two training sessions we have had have gone very well. It is very clear that the players want to learn and advance as a group.
"The tactical and technical work we did today was done very slowly so I could explain to the players exactly what it is I am looking for from them.
"Over the week in Portugal, we will do a lot more work at a greater intensity, and I am happy that we will be ready for the match against Serbia."
Ireland will face Serbia at Croke Park a week on Saturday in Trapattoni's first friendly at the helm, and meet Colombia at Craven Cottage the following Thursday.
They will also play games against Portuguese sides Portimonese and Lagos during their time in the Algarve as the manager attempts to stamp his authority on the squad.
Trapattoni said: "The players have the enthusiasm and the willingness to play.
"We will look at their conditioning [in the Algarve] and we have two friendly games arranged so we can check their form.
"We will know from that if they need more training or less training. This is because they have come in after the year's campaign [with their clubs].
"This is important so that we can arrive at the games against Serbia and Colombia in good shape."
