GEELONG will be without All-Australian full- back Matthew Scarlett for this week's match against Port Adelaide after scans confirmed the veteran would miss at least two weeks with a slight hamstring tear.

Shannon Byrnes will also miss with a foot injury sustained during last week's win over North Melbourne.

Harry Taylor and Joel Selwood will come into the side while Josh Hunt is available for selection after missing two weeks with a shoulder injury.

Cats coach Mark Thompson said the acid would be on his defence in the absence of Scarlett and All-Australian centre half -back Matthew Egan.

"It's a huge challenge," he said.

"We're coming up against a good forward line this week and we go to Perth the following week. The boys have really got to group up and work together and learn to play without Matthew (Scarlett)."

In assessing his club's opening 11 rounds the Cat coach said the team was perfectly placed to defend its premiership title.

"We're exactly where most clubs would want to be," he said.

"I just like our professionalism and our attitude to win games and keep our standards up. "I know that we haven't played four perfect quarters of football many times this year but when it's been needed I've loved watching them claw their way back and scratch through a game. They still have that competitive spirit about them."

One man who certainly has the competitive spirit is key forward Cam Mooney, who escaped the match review panel's wrath after an altercation with North defender Scott Thompson last week.

Thompson admitted Mooney treaded a fine line.

"We worry every game," he said about Mooney's penchant for silly indiscretions.

"It is a concern. He needs to be fired up but he's got to control his aggression too.

"He needs to be somewhere near the line to get the best out of himself and he likes living in that zone.

"I think Cameron has addressed it with some of his teammates and the coaches.

"He's just got to be so careful, and I think he understands now how much that could hurt the team."