Sam Bennett remains with the Calgary Flames to start the season, but when he'll make his NHL debut is unclear.

The 18-year-old forward has a shoulder injury that requires surgery. The Calgary Flames tweeted the surgery will take place next week and a full recovery is expected to take up to six months.

The Flames drafted Bennett fourth overall in this year's NHL draft, making him the highest selection in Calgary's history.

He was limited to three pre-season games and missed parts of main camp because of a groin injury coming out of rookie camp, which was followed by his shoulder troubles.

"I had problems with this shoulder last year," Bennett said in a previous interview. "I didn't think anything of it. I played through it all year. It started to act up a little bit at the start of camp this year."

When Bennett did get into games, he demonstrated the offensive flare that made him a high draft pick. He put seven shots on net and had an assist in his first pre-season game against Vancouver.

'I wanted to play'

From behind the net, Bennett set up Josh Jooris for a one-timer and Calgary's fourth goal in the team's last pre-season game at home.

But the six-foot-one 180-pounder from Holland Landing, Ont., didn't travel with the Flames to Winnipeg this past Saturday for their final exhibition game.

Bennett's entry-level contract kicks in when he plays his 10th NHL game. The Flames could keep him for up to nine games and then send him back to the Ontario Hockey League's Kingston Frontenacs.

Bennett has admitted previously he kept quiet about his shoulder pain because he wanted to be in the Flames' lineup.

"I wanted to play," he said at the time. "I'd do anything to make the team and play in the NHL this year. I didn't think it was that big a deal and it was a little bit bigger of a deal than I thought."

Calgary opened the regular season Wednesday night at home with a loss against the Vancouver Canucks.

With files from The Canadian Press