Aston Villa's James Collins has withdrawn from the Wales squad for their Carling Nations Cup matches this week with a groin injury.
The 27-year-old will be replaced by youngster Adam Matthews, who is joining Celtic from Cardiff this summer.
Adams is the fifth additional player to be brought in since manager Gary Speed named his initial squad for the matches against Scotland and Northern Ireland in Dublin.
Owain Tudur Jones replaced David Edwards at the weekend while Craig Morgan, Andy Dorman and Jermaine Easter were summoned last week.
They came in after Lewin Nyatanga and Ched Evans were injured and the progress of Swansea and Reading to the Championship play-off final denied Speed the services of Ashley Williams, Joe Allen, Simon Church and Hal Robson-Kanu.
Collins pulled out after playing all 90 minutes of Villa's season-ending Premier League victory over Liverpool on Sunday.
His central defensive partner in that match, Richard Dunne, also suffered an injury and withdrew from the Republic of Ireland squad on Monday.
Wales, having lost to the Republic in their first Nations Cup match in February, face the Scots on Wednesday and Northern Ireland 48 hours later.
The squad were due to fly to Ireland on Tuesday afternoon but have made contingency plans to travel by ferry should the ash cloud situation worsen.
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