When the sides met in the league earlier this season, Llanelli came out narrowly on top with a 27-23 victory.
And the Wizards have a score to settle with the Scarlets after their only appearances in the finals of 1974 and 1975 ended in defeat by this weekend’s opponents.
Neath, the present cup holders, were the very first winners back in 1972 and they face a Swansea side in the second match of the day (kick-off 5.20pm) who last reached the final in 2000.
The Welsh All Blacks already have a league victory over the All-Whites this season and could become the first club to retain the trophy since Llanelli triumphed in 1991, 1992 and 1993 if they can find their way to the Millennium Stadium final to be played on 9th May .
Sunday, 19 April.
SWALEC CUP semi-finals (at Liberty Stadium)
Aberavon v Llanelli (3.15pm)
Neath v Swansea (5.20pm)