The Welsh side produced the shock of the opening weekend of the Heineken Cup when they produced a 26-20 win over Racing Metro in the outskirts of Paris last weekend.
London Irish, who picked up a losing bonus point in after their narrow 20-19 home defeat to Edinburgh, will want to get their show back on the road after the disappointment of losing at home.
The Blues, who reached the final of the tournament in 1996 and a semi-final in 1997 and 2009 and won the Amlin Challenge Cup in 2010, will be without injured centre Jamie Roberts for the clash in the Welsh capital.
This will be the first time the two sides have met in Europe and the home side have an impressive victory on their home patch and have only lost once in their last 14 games in Cardiff.
Irish have lost their last four away games in Europe and will travel to Wales knowing they need to get their campaign back on track if they are to keep their hopes for a quarter-final place alive.
