Last year saw the Blues win the Under 18 age group competition while the Ospreys claimed the U16 title after a dramatic 32-29 win over Blues South.
The Blues kick off their U18 campaign against the Dragons at Abercwmboi RFC looking for another successful campaign.
Richard Hodges' men go into the U18 championship on the back of a brilliant pre-season having registered victories over Northampton, Gloucester, Munster and Leicester.
"We're ready but selection has been very difficult and there are a lot of disappointed boys," said Blues performance manager Richard Hodges.
"But we've picked a side that will give us the best chance of a win although we're placing a lot of importance on our style of play.
"Our aim is to challenge the opposition with ball in hand."
Ahead of the start of the competition, WRU National Performance Manager Gethin Watts is once again looking forward to seeing the best of the country's young talent in action.
"We are really looking forward to the new regional competition kicking off this week," he said.
"I know that all the regions have been working extremely hard during the summer to prepare the players in the best way they know possible and everybody is looking forward to seeing the fruits of their labour in the campaign coming up.
"The regional competition is a great breeding ground for young players and a great talent identification process for the national Under 18 squad selectors who I know will be out in force in the coming weeks to identify players for the national U18 programme."
Elsewhere, the Under 16 championship kicks off next Wednesday (September 5) with defending champions Ospreys taking on the Scarlets.
The Ospreys snatched victory from the jaws of defeat against Blues South in last year's final after trailing 22-6 at half-time but a second half blitz saw them eventually prevail 32-29.
But Ospreys Performance Programme Manager Andrew Millward is more concerned with the region's development than any silverware.
"It's more about the development at this point," he said.
"Every year we have new players so it's hard to transport success from one year to another. It's nice to win the Championship but it's not the be all and end all."
Opening round of fixtures in U16 Championship (Wednesday 5 Sep 7.15pm): Blues South v Dragons (Leckwith Stadium), Ospreys v Scarlets (Llandarcy)
Opening round of fixtures in U18 Championship (Wednesday 29 August 7.15pm): Blues v Dragons (Abercwmboi), Ospreys v Scarlets (Llandarcy)
1 Leon Crump
2 Liam Belcher
3 Dillon Lewis
4 Mike Snook
5 Ollie Hitchins
6 Jordan Viggers
7 Sam Parker (c)
8 Hemi Barnes
9 Tom Williams
10 Tom Mcaloon
11 Ellis Wyn Benham
12 Sam Edwards
13 Garin Smith
14 Kent Birch
15 James Whittingham
16 Ryan Spriggs
17 Rob Lewis
18 Gus Mcpherson
19 Brad Llewellyn
20 James Sheeky
21 Chris Brace
22 Jarod Evans
23 Ollie Smyth