Tuilagi will miss the RBS 6 Nations clash at Twickenham with the ankle injury that has prevented him from participating in a practice session since his withdrawal from the build up to the Tigers' victory over Toulouse eight days ago.
The explosive 21-year-old is expected to resume full training by the middle of next week and has a chance of returning against Ireland on February 10.
Lancaster, who has already decided who will partner Brad Barritt in the centres for the Calcutta Cup showdown, is refusing to take any shortcuts in the recovery of his most dangerous player.
"Manu has a high ankle sprain which is one of those injuries that can settle quickly, or take longer," he said.
"We want to make sure Manu is right and doesn't rush back and break down again. It's one of those injuries that can go again.
"It's taken until now to get him to run in a straight line. One of Manu's strengths is changing direction and we want to make sure he can do that without suffering a recurrence."
Tuilagi was devastating during last autumn's record 38-21 victory over world champions New Zealand, scoring one try and creating two more, and when fit has been an ever-present since making his Test debut in 2011.
Lancaster will announce on Thursday whether the inexperienced Billy Twelvetrees or Jonathan Joseph will partner Barritt with fly-halves Toby Flood or Owen Farrell also possibilities.
Twelvetrees would start at inside centre with Barritt switching to outside, while Joseph would be a straight replacement at 13. Flood can play at 12, while Farrell can fill both positions.
"I'm not sure there is a like for like replacement for Manu. All options are open. The reality is we haven't trained this week yet," said Lancaster.
"One of the options is to play Jamie (Joseph) at 13. He's been playing full-back for London Irish for the last three or four weeks.
"I don't think it's too early for Billy Twelvetrees to come in. I don't think I've worried in the past about that.
"I don't see a lack of international experience as a barrier to selection, it's about what's best for the team."
Lancaster confirmed that prop Corbisiero will miss the entire Six Nations following knee surgery that was initially expected to rule him out of only the opening two games.
"Hopefully Alex will be back around the final game against Wales, but the reality is he'll have to play two or three Premiership games first," he said.
"It's a shame because everything I heard about the operation was positive, but it's going to take a while to get right. Everyone's upbeat about his recovery."
Lancaster confirmed that Saracens full-back Alex Goode is available to start against Scotland after completing his comeback from a shoulder injury in the LV=Cup yesterday.
England enter the Six Nations as second favourites behind France, which represents a significant departure on last year when a shambolic 2011 World Cup resulted on a radical overhaul of the squad.
"The expectation now is on us, whereas this time last year we went up there with a new team. But the process remains the same," Lancaster said.
"We've had a lot of experience over the last 12 months and we must make that count on game day.
"The general mood is different because we've spent more time together and we understand better how we want to play the game.
"This time last year we were on the back of a World Cup that hadn't gone particularly well. There is a hugely different feel now.
"We've made England a place where people want to be, which is a great start. But no player will feel comfortable about his place in the team, which is also where you want to be."
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