"The Lions is at the back of everyone's minds, but you've just got to totally forget about that when you go on the pitch and play for your club," centre Roberts told Simon Thomas of the Western Mail.
"Personal ambition is set aside on a weekend like this. It's a big, important game and you need to totally black out anything to do with the Lions.
"It's all about the Blues. This is our job and the boys play for the badge."
Those sentiments were echoed by double Lions tourist Martyn Williams, who has been tipped as a near certainty for squad selection once more in 2009.
Having been on the wrong end of series defeats in 2001 and 2005, the 33-year-old openside would love to help the Lions return to winning ways in South Africa but he too recognises the importance of concentrating on the job-in-hand with the Blues.
"The Lions is on everyone's mind because everyone is talking about it, but you've got to realise as a player this is your bread and butter," said Williams.
"If the Lions ask you to go, then it's a huge bonus and everyone would jump at the chance.
"But we've got some massive games with the club first and we've just got to focus on them and not worry about what's going on outside your control."
Shanklin meanwhile is also adamant that selection for the Lions would be a bonus but that success with the Blues is his first priority.
The Welsh region have been in superb form in European competition so far this season, winning all six pool games and entering the quarter-finals as top seeds.
"Everyone keeps talking about the Lions tour, but that's at the end of the season," added Shanklin.
"You can't really think too much about the Lions. We've got a job to do this weekend and it's a big job because Toulouse are a class side.
"Right now we've got this week to focus on and it's a huge game for us.
"There are hopefully two or three big games left for the Blues this season. That's all we can focus on."