JACK Billings faces a race against time to play in round one after scans revealed a hamstring strain that will sideline him for four weeks.

The young St Kilda forward suffered the injury on Saturday during the Saints' three-point loss to the Brisbane Lions in the NAB Challenge match in Burpengary.

He limped off in the first quarter and didn't return.

It's the same hamstring the 19-year-old strained in round 20 last season, which ended his year early.

Click here for all the pre-season injury updates

The Saints' season opening match is on April 5 against Greater Western Sydney, just 33 days away.

Billings will miss the Saints' remaining NAB Challenge matches against Essendon (on March 7) and Hawthorn (on March 19).

The Saints are expecting to have Luke Dunstan (ankle), Tom Simpkin (knee) and possibly Daniel Markworth (shoulder) available for the clash with the Bombers after they missed Saturday's game.

But Jimmy Webster (finger) will miss another three weeks of training after surgery to fix a damaged tendon.

Arryn Siposs (shoulder) and Sam Gilbert (foot) won't play in the first month of the season and will be eased back through the VFL.

Meanwhile, the Saints have signed a third international scholarship holder from New Zealand.

Christchurch teenager Barclay Miller, a 195cm and 85kg sportsman, joins Joe Baker-Thomas and Giovanni Mountain-Silbery as Saints' scholarship holders from across the Tasman.

"Barclay has shown some impressive athletic attributes that we are confident will be transferred into football," St Kilda Recruiting and List Manager Tony Elshaug told the Saints' website.

“He was slam dunking at age 14 and dealing with being double teamed throughout his basketball days.

"He shows great awareness and agility, and we are looking forward to developing him through the AFL system."

Jack Billings is a $379,000 forward in NAB AFL Fantasy this year. Create and fill your AFL Fantasy Classic league by March 2 to win a free AFL Live pass.