Republic of Ireland skipper Seamus Coleman sat out training on Monday morning as manager Mick McCarthy launched his second spell at the helm.
Right-back Coleman, who played the full 90 minutes in Everton's 2-0 Premier League victory over Chelsea on Sunday, was rested and was joined on the sidelines by Preston forward Sean Maguire.
Central defender Shane Duffy was due to report later in the day after playing his part in Brighton's dramatic FA Cup quarter-final victory over Millwall.
Goalkeeper Keiren Westwood, defender Richard Keogh and midfielder Conor Hourihane were not scheduled to take part in the week's first session.
Ireland open their Euro 2020 campaign in Gibraltar on Saturday and face Georgia in Dublin three days later.