GEELONG will enter its first game of the 2008 season without premiership ruckman Brad Ottens after the bigman failed to recover in time from an ankle injury.

Ottens, 28, rolled his ankle in a VFL practice match last week, and senior coach Mark Thompson confirmed the ruckman's omission on Wednesday as the side prepared to depart from Melbourne Airport.

Geelong begins its title defence against Port Adelaide at AAMI Stadium in Adelaide on Thursday evening.

"He won't play. The team sheets go in at 12.30pm, so he's going to miss one week," Thompson said.

"We're really confident he'll be right for round two."

Emerging ruckman, teenager Trent West, will make his senior debut after two years on the Cats list.

Midfielder Ryan Gamble will line up for his second AFL appearance after playing one senior game at the end of the 2006 season, and Tom Hawkins will play his 10th match in the absence of Nathan Ablett.

Defender Max Rooke, who is on the comeback trail from a calf injury, will play in the VFL.

Thompson said the Cats had not experienced a different lead up to the season, despite holding the 2007 title.

"It doesn't feel different. The build-up has been pretty much the same," he said.

"We're sick and tired of the practice match series and we're looking forward to playing."

Thompson also said the players were anticipating a tough assignment first up, with the Port Adelaide players expected to come out hard in an attempt to make up for last year's Grand Final capitulation.

"It's always a hard assignment playing in Adelaide, and playing Port Adelaide, who are a really good team, makes it a very challenging game," he said.

"We've been in pretty good form and we go over there expecting a really competitive game and we're hoping we do really well.

"It's been a long time but obviously they would be [stinging from the Grand Final]. The one team they probably would really like to beat would be Geelong.

"We've had a good summer and we're really committed to play the best football we're capable of playing."