Sunday's gate will extend that as the highest ever pool attendance in Wales since the tournament began in 1995.
The Tigers have sold more than a thousand tickets and will have a strong presence at the ground where they won the Heineken Cup in 2002.
The Millennium stadium roof will be closed for the game, ensuring a great playing surface and a warn and dry atmosphere for the fans.
The Blues are hoping to break through the 22000 crowd that Leinster enjoyed at Lansdowne Road last weekend to set a season's high attendance. After that they will have the Heineken Cup Pool record of 34,000, for last season's match between Toulouse and London Wasps in their sights.
Tickets for the game will be in sale from the Cardiff Blues ticket office before the match.