Adelaide big man Sam Jacobs has nothing but praise for draftee Reilly O'Brien, who will assume the No.1 ruck mantle against Geelong on Thursday night.

Jacobs will play his first game of the year against the Cats after missing the Club's opening pre-season hit-out against North Melbourne in Port Lincoln.

The star ruckman jarred his medial ligament in January and will be managed in the lead-up to Round One.

Jacobs has been named in the All Australian squad of 40 twice in the past three seasons but will take a back seat to O'Brien, 19, at Simonds Stadium.

O'Brien impressed coach Phil Walsh in his first taste of AFL football against the Kangaroos, winning 14 hit-outs as well as gathering as eight disposals and three marks.

Along with O'Brien, Jacobs believes the development of rookie Jack Osborn and the arrival of Luke Lowden from Hawthorn had quickly established a quality, albeit underrated ruck department at Adelaide.

"I just think for a bloke who's come straight out of the under-18 system and probably hasn't had to play against men, I thought Reilly competed really well against the Kangaroos," Jacobs said.

"From a team perspective he did all we could ask - he gave a lot of effort, he marked well, so I think there's some really promising signs.

"Jack Osborn's another one who's starting to get into it, he's a really good athlete as well.

"We've got a pretty exciting little ruck group working together and I'm excited to hopefully teach them a little bit about it as well.

"They're definitely making me a better player … they're all fresh so they're all looking for that opportunity which is a good thing."

Jacobs was sensational last year at a time when most of his teammates struggled for consistency.

As was the case in 2012, he was unlucky to miss out on All Australian honours given he averaged 35 hit-outs and 16 disposals a game.

His recent knee injury has proved a slight setback, but he had previously enjoyed a flawless pre-season and was confident he could raise the bar again this year.

"The injury was (in) early January, so I had a really good hit-out before the injury and I feel like I've been able to retain my running standards," he said.

"I could have played in Port Lincoln but it's just a matter of managing loads.

"I learnt a fair bit last year in terms of how to prepare and I'm better for it.

"I've had really good preparation and I'm looking forward to the chance to back it up."