"It looks like an (ankle) injury that will be for four to six weeks before it is right," his coach at club Gloucester Nigel Davies said.
"It’s not ligaments, it’s a relatively minor injury."
With that timescale, Twelvetrees will stand little chance of making the first test in Auckland on June 7 and will have to prove he is likely to be fit for the second in Dunedin a week later to stand any chance of making the squad.
The 25-year-old joins an absentee list that includes prop Alex Corbisiero, flanker Tom Croft and wingers Jack Nowell and Christian Wade, who are all recovering from injuries, and hooker Tom Youngs, who has been given compassionate leave.
Lancaster already had to cope with a complicated selection dilemma thrown up by the fact that none of the players involved in the Premiership final on May 31 will be available for the first test a week later - potentially depriving him of another half dozen and making an already difficult task considerably harder.
A fit Twelvetrees, a regular in the side over the last year, would have been a certain starter as Gloucester’s season ends with their final Premiership game at Worcester on Saturday.
(Reporting by Toby Davis; Editing by Mitch Phillips)
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