A decision on the two games will be made later today in a bid to prevent the two North Wales sides making a fruitless journey south.
The Ospreys under 16s have fallen off quite alarmingly after a decent start to the season - early victories over Blues South and the Dragons, have given way to three straight defeats.
However, with home advantage in their favour, the region will be confident of inflicting a fourth defeat of the season on a Gogledd Cymru side that has shown marked improvement since the beginning of the campaign.
Anything less for the Ospreys and their hopes of reaching the final of this season's competition will once and for all disappear.
The side is currently lying in third place with 12 points from five games. They are nine points behind second placed Blues South and 11 adrift of the table-topping Scarlets.
The Ospreys U18s are also in desperate need of a victory having slipped unceremoniously into fourth place, a point shy of the Dragons, eight points behind the Blues and 13 behind the Scarlets with two games remaining.
Like the U16s, they too have lost their last three games, against the Blues, Scarlets and Dragons and a fifth defeat of the season on Sunday, will put paid to their slim hopes of reaching the final.
Will Morecombe, team manager at Gogledd Cymru Under 18s said; "We are developing well at both age groups, but it doesn't get any tougher than a Sunday afternoon against the Ospreys away from home.
"Having said that, if we are going to continue to improve, it is games like this that will help the boys to reach the next step."
Gogledd Cymru U18s: I Ellis; H Roberts, B Stemaleszk, N Hughes, I Phillips; J Williams, A Schwarz; O Hughes, J Williams, E Mason, J Simm, C Holmes, G Jones, G Morgan, B Powley. Replacements: J Matthews, M Bevan, L Williams, M Downey, J Hughes, O Aled, W Mitchelmore
Gogledd Cymru U16s: D Jones; A Evans, M Jones, R Williams, M Richards; L Barker, A Bagshaw; J Simpson, R Kirby, T Rowlands, A Gwyn, J Meadows, M Parry, J Grundy, R Jones. Replacements: R Evans, G Pym, L Evans, M Francis, P Roberts, J Blackmore, T Brittain