THE signs were ominous for Carlton's back line yesterday even before the ball was bounced to start the match.

Setanta O'hAilpin was penalised after Fremantle captain Matthew Pavlich fell to ground and the Irishman's protests led to a 50-metre penalty and certain goal to the visitors.

Less than an hour earlier the Blues confirmed what many already suspected, withdrawing key defender Bret Thornton from the side after failing to convince the coaching staff he'd fully overcome a strained medial ligament.

Into the team came 20-year-old Darren Pfeiffer for just his sixth senior match.

The former South Australian worked himself into the contest playing mostly in attack and finished with 11 disposals and a goal in the dying stages, which he later described as "right up there as the best moment" of his short AFL career.

With Thornton contemplating a return next week against Geelong it was left to O'hAilpin to quell the influence of Pavlich and Paul Bower, in his 21st game, to limit Chris Tarrant.

In his 188th game Tarrant was switched on from the moment he walked onto the Telstra Dome surface, collecting five disposals and three marks by quarter-time, although importantly for Carlton the 27-year-old was held goalless.

Andrew Carazzo, who started his AFL career in defence before working up the field, started back with instructions to curb mercurial Dockers forward Jeff Farmer, while Jarrad Waite, in his 94th game, was the most experienced of the Blues' back six.

Carazzo's goal on the run midway through the final term was the Blues' first since the 18-minute mark of the third quarter and helped turn the match, but his blanketing job on Farmer for much of the game drew stronger praise from coach Brett Ratten.

"His role on Farmer, keeping him to two (goals) I thought helped strengthen us up," Ratten said, before saying it was the club's youthful back line that helped win the day. "I know (Fremantle) players kicked goals, but Setanta's role and Bower and Waite were the three I thought really stood up today. I thought they were great for us.

"We knew we had to stop their forwards and I thought they stuck to their tasks all day.

"We've put a lot of kids through there at times, (Bryce) Gibbs has been down there, (Jordan) Russell and (Shaun) Grigg have been down there and they're developing really well — everyone is taking on the responsibility while they're down there."

For Bower that responsibility meant cutting off delivery to Tarrant, who he rates as the fastest player on the burst he's come up against. Tarrant finished with nine marks and three goals, but Bower never left his side and made the former Magpie earn every touch.

"He's lightning quick and once he gets out of the blocks he's hard to catch, so it was a good challenge for me and another step for me to play on such a good player," he said.

"It would have been nice having Bret back there with his experience, but I thought we held our own in the end and it was just great to get the win."

The nine-point victory was the Blues' first against Fremantle since round 16, 2001, and one the defensive set-up can rightly claim as an important scalp.

Like the Western Bulldogs the week before at Subiaco, Bower said the Blues spoke about Fremantle's poor record in the final term, which has seen it win just one final quarter this year.

"We knew we were under pressure in the last quarter, we were down, but knew if we fought out the game we could come back," he said.

His 11 disposals, two marks and two tackles might not feature in a highlight's package of the match, but combined with Waite's 25 touches, Carazzo's 21 and O'hAilpin's relentless pressure, they helped the Blues to a valuable win.

"That was the real pleasing thing for us today," said forward Brad Fisher. "A few of our starting back six aren't on the park at the moment, but the boys that are there really held up against a pretty good double act in Pavlich and Tarrant."