CARLTON utility Bret Thornton believes the Blues will face a stern test when they take on the Brisbane Lions at the Gabba on Thursday.

The Lions ran rings around Melbourne in the second half of their season opener last week, which Thornton said was a more accurate indication of their strength than the poor form of 2011.

"They were very impressive; they've got some really good young players playing well, and it was only a couple of weeks ago that they beat us by 12 goals [in the NAB Cup] up at Maroochydore," Thornton said from Melbourne Airport on Wednesday.

"Although the personnel is probably going to be a bit different this time we're definitely not going to take them lightly. It's going to be a very hard game.

"I think their young players have had a really good pre-season, [Tom] Rockliff and [Claye] Beams and those sort of guys; they've got another pre-season under their belts and it's already starting to show good signs for them."

The Carlton veteran was impressed with the early-season form of Rockliff, who booted three goals in the big win against the Demons.

"He has an impact in the midfield and then he can push forward," Thornton said.

"He's been compared this week to [Jimmy] Bartel … he's a weapon in the midfield and up forward so we'll need to be on our guard for sure."

Carlton coach Brett Ratten said the Blues were impressed with the Lions’ 41-point round one victory over Melbourne.

"Some of their patterns of ball movement were outstanding and their fitness levels were at a very high standard, so I think it'll be a great game,” Ratten said.

"We really respect what they're doing and some of their players, especially their younger players, are really coming on and playing fantastic footy at the moment."

Ratten also revealed he had spoken with his players about the topsy-turvy nature of recent matches between the sides at the Gabba.

In 2008, the Blues overcame a 32-point three-quarter-time deficit to win, while just 12 months later in the first week of the finals, the Lions came back to win from 30 points down early in the last term.

"Our rivalry with Brisbane a couple of years back, it was 10 points either way at certain times and they were fantastic games," Ratten said.

"Coming up here you know the crowd gets involved. It probably does help the home team.

"The game can shift up here really quickly and we've spoken about how the shifting of momentum in games is critical at the Gabba."