GEELONG'S decision to leave out regular ruckman Zac Smith and instead play star defender Mark Blicavs in the role against North Melbourne was based on the likelihood of wet conditions, according to coach Chris Scott.

Smith was a late withdrawal for the Cats' win over the Roos on Saturday night, with Geelong choosing to 'manage' the former Gold Coast big man and instead ruck with Blicavs, who shapes as an All Australian defender this year. 

It meant the Cats entered the game without a recognised ruckman, with Blicavs splitting duties with athletic forward Esava Ratugolea.

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Blicavs performed strongly in the role, collecting 13 disposals and managing 21 hitouts to veteran North ruck Todd Goldstein's 42, as the Cats steamrolled the Roos and kept them to one goal and their lowest score in the club's history (1.8). 

But Scott said it was the likelihood of wet weather throughout the contest that was a big factor in the decision to replace Smith with key defender Lachie Henderson, even though the rain did not fall until the fourth term. 

"Our assistant coaches laugh at me because I talk about the weather all the time. I thought it was going to pour with rain over in Perth [against Fremantle last week] and it didn't, so those decision are often tough. The conditions were much, much better than we expected them to be," he said post-game.

"Primarily that call was around the conditions. Blicavs played really well and we know that's an option for us and we've known that for a long time.

"But I wouldn't read into tonight as necessarily being the way forward for us in the ruck. It could be, but we're very open to the other options we've got there."

Scott said the decision to swap Smith out of the game was made "a couple of hours" before Saturday night's first bounce, with fellow ruck option Rhys Stanley playing in the pre-game VFL curtain-raiser. 

"It was more likely a couple of days ago but we just wanted to hold on to the decision a little bit," he said.

The Cats continued their up-and-down form line since their round 13 bye, and will next week face the second-placed Brisbane at the Gabba in a top-of-the-table clash.

Scott praised youngster Quinton Narkle for his return to the senior side, with the exciting 21-year-old kicking two goals from 21 disposals in his first senior game of this season.

"Narkle coming in at this time of the year is not a reflection of trying to get a bit of youth into the team. It's a reflection of what we think our best team is right at the moment, and he certainly delivered on that," he said. 

Geelong is fighting for a top-two finish on the ladder, with next week's trip to Brisbane crucial in its push after a brilliant start to the season.

Scott believed the comprehensive win over the Roos, which once again underlined his side's status as the best defensive unit in the AFL, was a step in the right direction.

"Mojo's important heading into the end of the season, and I don't think one week gets it back necessarily," Scott said.

"But we did need to play better. We weren't running away from the fact we weren't playing as well as we would've liked but at the same time we didn't buy into the fact that we were in a big hole. 

"Even more than the win-loss, the issue that we had was we would've liked to have been playing more in our style. I thought tonight was a better reflection of that."