There was more bad news for the Giants with confirmation Phil Davis and Matt Buntine have been sidelined with injury, placing extra pressure on the club's backline stocks.

In what has come as a shock to the Giants, Hopper will miss six weeks after scans revealed an "incomplete stress injury" in his back. The academy graduate now faces a race against the clock to regain his place for the finals. He will not return before round 21 and will need time in the reserves to regain match fitness.

Hopper starred on debut with 32 possessions but his form gradually tailed off before he was left out of the team last week to manage his workload.

"Jacob had some discomfort in his back and due to the nature of the issue and his history, he underwent scans that revealed an incomplete stress injury," the Giants' head of athletic performance David Joyce said.

"This is disappointing news as Jacob had made a great start to his AFL career this season but due to his age and the stage of his career, we'll be taking an aggressively cautious approach. We're pleased that we caught the issue early and we are confident that with conservative management and rehabilitation, he'll be back playing football later in the season."

Davis has suffered another injury setback, this time breaking down with a calf strain that will keep him out for two to three weeks. It is the second soft tissue injury for the Giants captain, who has managed 69 of a possible 102 games since the club's inception.

Buntine will miss three weeks with his hamstring strain, which has proven to be worse than what the Giants had initially thought.

The Giants have been hit hard with injury to their defence this year with Caleb Marchbank, Tim Mohr and Aidan Corr all missing lengthy periods. Marchbank and Mohr are set to come back after the bye though may need to come back via the reserves.

Adam Tomlinson and Adam Kennedy are both in the frame to cover for Davis and Buntine.