The Football Association of Wales (FAW) is considering organising a home friendly against Northern Ireland ahead of the Euro 2016 qualifier against Belgium on Friday, 12 June.
Chris Coleman's side are second in Group B, one point behind Israel and three points ahead of World Cup quarter-finalists Belgium.
Wales drew 0-0 in Brussels in November and next travel to Israel on 28 March.
They could play Northern Ireland on Thursday, 4 June or Sunday, 7 June.
Group favourites Belgium have already confirmed they will play a friendly against France on Sunday, 7 June.
|Wales' remaining Euro 2016 qualifiers|
|28 Mar 2015: Israel (a)||6 Sep 2015: Israel (h)|
|12 Jun 2015: Belgium (h)||10 Oct 2015: Bosnia-Hercegovina (a)|
|3 Sep 2015: Cyprus (a)||13 Oct 2015: Andorra (h)|
A lack of match fitness leading into the Belgium game is a potential concern for Coleman with the Premier League season ending on 24 May - nearly three weeks before the qualifier.
The Championship season finishes on 2 May and unless players are involved in the Football League play-offs, it means they would have a six-week break before the qualifier against Belgium.
Wales have made an unbeaten start to their Euro 2016 qualifying campaign with two wins and two draws.