SAM Gilbert has suffered a minor setback to his pre-season training after being sidelined with a stress fracture on his left foot.

Gilbert, 27, underwent surgery on his metatarsal bone this week and had a screw inserted after injuring himself during a training drill.

Head of Football Chris Pelchen said Gilbert would be unavailable for the NAB Challenge matches against Western Bulldogs, GWS and Port Adelaide.

“It’s disappointing for Sam, particularly because he has had a solid pre-season to date,” Pelchen said.

“But he is anticipated to re-commence training in approximately six weeks, with his availability for Round 1 of the AFL season still to be determined.”

The defender returned for the last three matches of the 2013 season after being sidelined with a knee injury in round six against Collingwood.