The Blues' nearest challengers, Llanelli, are also at home on Friday with Ulster the visitors to Stradey Park. The former champions, beaten by Edinburgh and the Dragons in recent weeks, have had a poor start to their season and are currently in an unaccustomed last place in the league with only one win to their name.
The Scarlets have a proud record in the league at Stradey Park against Irish sides, and Ulster have never won on the Scarlets' patch.
Andy Robinson saw his Edinburgh side draw with the Ospreys in his first match in charge last weekend while their opponents on Friday night, Newport Gwent Dragons, pulled off something of a shock last Saturday by recording their first win of the season over Ulster. The Scots however have won five of their last six encounter with the Dragons.
Friday's final game pits Glasgow Warriors against Leinster with the Warriors having lost just once in the league at home since the start of last season. Leinster however will be looking for a quick return to winning ways after losing their long-standing 16-match home record to the Scarlets last week.
Sunday afternoon sees the last game of the round with Munster, smarting from a narrow loss to Cardiff last weekend, facing the Ospreys in Swansea. After a shaky start, the Ospreys have picked up a win and a draw in their last two outings and will be looking for a third successive win over Irishmen at the Liberty Stadium.
ROUND 4 FIXTURES:
Friday, October 12:
Llanelli Scarlets v Ulster, Stradey Park, 7.10pm (live BBC Wales/Setanta Sports)
Cardiff Blues v Connacht, Arms Park, 7.30pm
Edinburgh v Newport Gwent Dragons, Murrayfield, 7.30pm
Glasgow Warriors v Leinster, Firhill, 7.30pm (live Setanta Sports)
Sunday, October 14:
Ospreys v Munster, Liberty Stadium, 4.10pm (live S4C/Setanta Sports)