Lake has recently undergone a minor shoulder operation, which adds to the knee and hip operations he had at the start of pre-season, while Hargrave has had a bone fused in his foot.
While both are on track for round one of the 2011 home-and-away season, their absence in at least the first two weeks of the pre-season competition will see new faces fill their roles.
"It will allow us to see who wants to play senior football," backline coach Peter Dean told afl.com.au this week.
"Lukas Markovic has been recruited for that role so he'll be able to show his wares in the NAB Cup. He's just getting over a shoulder operation so he's doing the running and not too far off ball work.
"Dale Morris and Tommy Williams will become the key backmen in Brian's absence and it will give the younger guys like Easton Wood the chance to step up with Jarrod Harbrow gone."
Dean said Brennan Stack, who has played in defence at times in the VFL, could also be trialled down back in February if his fitness improves.
Lake and Hargrave are the only two major injury concerns from the Dogs' back half, with the former to return to running in mid-January and the latter around Christmas.
"[Lake] is rehabbing with his knee from the scope and clean out, which was a little bit worse than we thought, so he's been biking mainly and will do that until just after Christmas and then he'll ramp up," Dean said.
"[Hargrave] has had a crook foot for four years and he's had a bone fused, which had been causing a fair bit of pain over a number of years and he's played through it.
"He's had that done now and he hasn't run yet but he's feeling less pain already."
Dean said Morris, who made a brave recovery for the preliminary final after suffering a back fracture, was moving well while Wood had improved on his time trial results for the second year running.
Lindsay Gilbee has returned to training lighter than usual while the injury-prone Williams "needs a bridle" after resuming fully fit and ready to go.
Dylan Addison is also training well after doctors decided he didn't require the knee operation he was initially booked in for.
The Bulldogs will head to New Zealand next week for a seven-day pre-season adventure camp.
