Also on Friday night the Newport Gwent Dragons travel to Galway to face Connacht, a team they have not beaten on the Irish soil since their first visit in 2004.
Benetton Treviso will travel to Firhill Stadium to face Glasgow Warriors. The Italian outfit have not yet won outside of Italy in the RaboDirect PRO12, and Glasgow, having claimed a surprise win at Leinster last weekend, must be looking to consolidate on that performance.
The Scotland v Italy theme continues on Saturday, but this time the action moves to Italy when Aironi welcome an Edinburgh team who will remember that they lost on their last visit to the country - 31-6 to Benetton Treviso in May.
The Scarlets and Leinster are also in action on Saturday. Neither side has had a very good start to the season. Both of them have a won 1 lost 2 record and are sitting the wrong side of the play-off zone, so they will be looking for a win to get their campaign back on track.
The round wraps up on Sunday afternoon, with the RaboDirect PRO12's other two unbeaten teams, the Ospreys and Ulster, battling it out at the Liberty Stadium.
Both teams have been building up impressive records from the end of last season, however if home advantage is anything to go by, the Ospreys have the edge on that having won five of the sides' seven encounters at Liberty Stadium.
RABODIRECT PRO12 - ROUND 4 FIXTURES:
Cardiff Blues v MUNSTER, Cardiff City Stadium, 7.05pm (live RTÉ Two/BBC 2 Wales)
CONNACHT v Newport Gwent Dragons, the Sportsground, 7.30pm
Glasgow Warriors v Benetton Treviso, Firhill Stadium, 7.30pm
Saturday, September 24 -
Aironi Rugby v Edinburgh, Stadio Zaffanella, 3pm
Scarlets v LEINSTER, Parc y Scarlets, 6.30pm (live TG4/S4C)
Sunday, September 25 -
Ospreys v ULSTER, Liberty Stadium, 4.30pm (live S4C)