Newport Gwent Dragons and Scarlets reached the Anglo-Welsh Premiership Sevens final in the Welsh regional round in Cardiff.
Dragons' Elliott Frewen touched down twice in the final game against hosts Cardiff Blues as they won 31-19.
Ospreys beat Blues 33-24 before Scarlets beat Dragons 24-19.
Dragons' 31-14 win over Ospreys was followed by Scarlets beating Blues 25-6. Ospreys beat Scarlets 17-12, but and Dragons claimed the Welsh spoils.
Scarlets will join their east Wales counterparts in the finals involving England's leading teams at Twickenham Stoop on Friday, 28 August.