Warburton, last season's Wales U19 captain, will miss the first two rounds of U20 matches later this month after undergoing knee surgery.
However, the Union has worked with the Regions and the Premiership clubs to ensure the best players at U20 level compete in the Regional U20 Championship, which means the competition is sure to be even better this time around, according to Warburton.
"I have enjoyed the first two years and can't wait to get underway. For me, it's likely to be October before I can play, but I will be there shouting the guys on in their opening matches against the Scarlets and Ospreys," he said.
"The fact that the best players are going to be available for the matches means that the competition for places and the challenge to win the trophy will be even greater than it has been."
Another leader of last season's successful Wales U19 side, Scarlets lock Josh Turnbull is looking forward to competing against his peers for selection for this year's U20 squad.
"The Reebok competition has been instrumental for my development in terms of getting into the international age grade sides. Along with the Principality Premiership, we are all focussing on this tournament to stake our claim for places in the U20 squad for the Six Nations and Junior World Championships."
Turnbull sits out tomorrow's match against the Blues but there will be a chance to see Llanelli and Wales U19 fullback Daniel Evans at outside half for the Scarlets, while new Blues signing, Queensland Reds Academy product Luke Evans, gets its first start in Wales at scrum half for the Blues.
The U20s are in action again next Tuesday, with the Scarlets hosting the Dragons at Narberth and the Ospreys taking on the Blues at Llandarcy.
Blues: L Halfpenny; B Warburton, F Edwards, L Ford, N Rees; J Thomas, L Evans; S Hobbs, H Dowden, S Andrews, J Porter, M Al-Azzawi, J Groves (Capt), D Franks, K Dacey
Replacements: M Howells, T Price, P Palmer, M Gardner, J Thomas, H Allen, L Williams
Scarlets: R Cuniffe; M Lemon, J Harries; R Williams, T Rees; D Evans, J James; G Robinson, T Wilson, M Evans, H Pugh, J Kierney, D Zangouras, N Cudd, L Phillips (Capt
Replacements: G Flynn, S Thomas, C Jenkins, A Harries, L Owen, M Gibson, D Watts
Dragons: B Howells; N Preece, J Hannam, G O'Driscoll, L Cole; J Tovey, J Leadbetter; W Griffiths, N Buck, C Fillier, A Sweet (capt), D Morgan, L Bray, S Horton, S Pailor
Replacements: L Harwood, R Cadagon, S Maguire, G Smith, T Edwards, G Dare, S Skinner
Blues v Scarlets (Cardiff Arms Park 7.15)
U20 Round 1 fixtures: Wednesday September 12th
Dragons v Ospreys (Rodney Parade 7.15)
U20 Round 2 fixtures: Tuesday September 18th
Scarlets v Dragons (Narberth RFC)
Ospreys v Blues (Llandarcy Academy)
U18 Round 2 fixtures: Wednesday September 19th
Blues v Ospreys (Llanharan RFC)
Dragons v Scarlets (Abertillery RFC)