Cardiff Blues North U18 and Cardiff Blues South U18 have confirmed their sides for the mid-week clashes in the Regional Age Grade Championship.
Both sides have made numerous changes from last week's inter-region derby at Sardis Road, where Cardiff Blues South came out on top with a 20-0 victory.
North will take on Dragons tonight at the Centre of Sporting Excellence in Ystrad Mynach (KO 7.00pm), while South face their Ospreys counterparts on Wednesday at the Brewery Field in Bridgend (KO 7.00pm)
There are seven changes made in the North side, who introduce a new-look front row of Garyn Phillips, Ieuan Morris and Iestyn Haskins.
Elsewhere in the pack, Cian Lewis-Hughes makes a switch to blindside flanker, allowing lock Archie Trevethan to replace number eight Ieuan Pring.
There are three changes in the backline, with Josh Oakley and Cavan Slade forming a new half-back partnership.
Rhys Davies switches from outside half to outside centre, with wing Dafydd Thomas replacing Iwan Price Thomas in the back three.
Four changes are made to the South side, as Max Lucas replaces Owain Harvey in the number two jersey.
Dylan Rigby comes in at number eight, in place of Aaron Churchill, while Craig Miller and Joe Davies are reintroduced to the backline.
Cardiff Blues North U18 to face Dragons U18 (Tuesday, 16 January, 7.00pm, Ystrad Mynach's CSE):
Liam Lloyd; George Thomas, Rhys Davies, Joe Vickers, Dafydd Thomas; Cavan Slade, Josh Oakley; Garyn Phillips, Ieuan Morris, Iestyn Haskins, Archie Trevethan, Mitchell Barnard, Cian Lewis-Hughes, Callun James, Ioan Davies
Replacements: Aneurin James, Matthew Isles, Fraser Hughes, Lloyd Gregory, Cerith Lloyd, Nathan Griffiths, Jack Harvey, Ioan Evans
Cardiff Blues South U18 to face Ospreys U18 (Wednesday, 17 January, 7.00pm, Brewery Field, Bridgend):
Ioan Davies; Jay Jones, Joe Patterson, Craig Miller, Joe Davies; James Beetham, Joe Williams; Joe Melhuish, Max Lucas, Adam Conway, Lewis Jameson, Teddy Williams, Ellis Reid, James Bartlett, Dylan Rigby
Replacements: Harry Boxhall, James Sken, Harry O'Connor, Emyr Jones, Jake Hillman, Ioan Lewis, Llew Rhys, Drew Stephens