Flynn has seen seven former squad members promoted to the senior side, including £10m-rated Gareth Bale.
The friendly kicks-off Wales's build up for the 2009 Uefa U21 Championship qualifiers, the draw for which will be made next week in Stockholm.
"We are looking for the new generation to come through as show what they are capable of," said Flynn.
"So many of the younger lads have already made the jump into the full international set-up that I am able to give opportunities to the under-19s and under-17s
"There is now an opportunity for development, we are showing many of these lads an open door to a senior international career, and it is up to them to walk through it.
"They can see what has happened to the likes of Gareth, Lewis Price, Lewin Nyatanga and Joe Ledley from the previous under-21 squad, and it is up to the new lads to grasp the opportunity presented to them."
Flynn has lost Swansea's Shaun MacDonald and Chesterfield's Kyle Critchell from his original squad through injury, and has called in Crewe's Chris Flynn and Middlesbrough's Rhys Williams.
Australia-born Williams, 18, recently discovered he qualifies for Wales through a Welsh grandfather.
"I had no idea I had Welsh ancestry until a few weeks ago. My Dad phoned me to say I had a Welsh grandfather," said defender Williams, who is also eligible to represent England and India.
"I had never met him before but we did a bit of a research and the next thing I knew Brian Flynn wanted me in the squad."
Flynn says he is looking in particular commanding performances from Shrewsbury's David Edwards and Cardiff's Chris Gunter.
Midfielder Edwards, 18, has been a regular for Shrewsbury this season, scoring five goals, while 17-year-old Gunter has made four Championship appearances for the Bluebirds.
"These two, plus goalkeeper Wayne Hennessey, are players I am looking to see force their way into the senior squad sooner rather than later," added Flynn.
Wales Under-21 squad to play Northern Ireland at the Oval, Belfast on 6 February (1500 GMT):
Wayne Hennessey (Wolves), Owain Fon Williams (Crewe), Mark Bradley (Walsall), Kyle Critchell (Chesterfield), Chris Gunter (Cardiff), Joe Jacobson (Cardiff), Mike Williams (Wrexham), Darcy Blake (Cardiff), Mathew Collins (Fulham), Rob Davies (WBA), David Edwards (Shrewsbury), Dean Grubb (Bristol City), Lloyd James (Southampton), Rhys Williams (Middlesbrough), Owain Warlow (Lincoln), Chedwyn Evans (Man City), Chris Jones (Swansea), Sam Vokes (Bournemouth).