S4C will show each of the derby matches between the Welsh rugby regions during the first three rounds of the Rainbow Cup.
All six derby matches in the new competition will be shown in full, as deferred broadcasts, by Clwb Rygbi.
In round one, Ospreys host Cardiff Blues at the Liberty Stadium on Saturday 24 April, with coverage being shown at 8.35pm.
On Sunday 25 April, Dragons take on Scarlets at Rodney Parade, with Clwb Rygbi coverage getting underway at 5.30pm.
Scarlets welcome Ospreys on Saturday 8 May, with coverage being shown at 9.40pm, while on Sunday 9 May, Cardiff Blues face Dragons at the Arms Park, with the match being shown at 5.30pm.
On Saturday 15 May, coverage of Scarlets v Cardiff Blues will be shown on 7.30pm, and on Sunday 16 May, full coverage of Dragons v Ospreys will be shown at 5.30pm.
Clwb Rygbi is produced by BBC Cymru.
Rainbow Cup on S4C
Round 1
Ospreys v Cardiff Blues – Saturday 24 April – 8.35pm on S4C
Dragons v Scarlets – Sunday 25 April - 5.30pm on S4C
Round 2
Cardiff Blues v Dragons – Saturday 8 May – 9.40pm on S4C
Scarlets v Ospreys – Sunday 9 May – 5.30pm on S4C
Round 3
Scarlets v Cardiff Blues – Saturday 15 May – 7.30pm on S4C