The Blues went down to an agonising defeat against Northampton to end their Heineken Cup dreams last weekend. But Roberts, who made his comeback in the loss, reckons the Blues have to bounce back with the resumption of Magners League action.
"Our focus switches to the Magners League now and it is important we bounce back in that competition," said 2009 Lions Man of the Series, Roberts.
"It's a huge period for the Welsh rugby teams and the fans watching us go head-to-head over the Christmas period.
"We have to come out all guns blazing, starting with the trip to Rodney Parade."
It is a crucial period in the Magners League with crunch local derbies in a busy festive period. First up for the third-placed Blues is the trip to Rodney Parade to take on Newport Gwent Dragons on December 27, before welcoming the Ospreys to the Cardiff City Stadium for a New Years Eve showdown.