The Lions slumped to their first-ever defeat to the New Zealand Maori in their third tour match in Hamilton.
A late Brian O'Driscoll try was not enough to save the Lions after Leon MacDonald had crossed for the inspired Maori in the second half.
The misfiring Lions spent much of the game defending and lost prop Andrew Sheridan to the sin-bin for a punch at the end of the first half.
The Lions turned around at 6-6 but were hit by a Maori maelstrom afterwards.
The Maori, without a win in six matches against the Lions stretching back to 1930, selected their strongest side ever after being allowed to have first call on every eligible player.
In response, Lions coach Sir Clive Woodward opted for the heaviest front row in Lions history at 54 stone, 10 pounds.
But the Lions, who face Wellington on Wednesday, were unable to cope with the Maori ferocity at the breakdown and the inspiration of Carlos Spencer as a replacement fly-half early in the second half.
The Lions won their opening two games against Bay of Plenty and Taranaki but with the first Test against the All Blacks approaching on 25 June, Woodward's side have problems to resolve.
The game got off to a tetchy, fractious start with both sides keen not to take a backward step in the opening encounters.
Maori fly-half David Hill missed an early penalty after 10 minutes when Lions open-side Martyn Williams failed to roll away from the tackle.
Shortly after, the Lions opened the scoring with a Stephen Jones penalty after Matt Dawson's sniping run.
The Maori hit back quickly through Hill when English prop Julian White was penalised for angling in at the scrum.
And the home side maintained their momentum with some aggressive defence at the breakdown to turn over Lions ball and spark a promising attack down the left, snuffed out eventually on the line by Jones.
The Lions were under threat again when Shane Williams spilled the ball after coming inside off his left wing and the Maori poured down the right flank, only to turn over the ball themselves.
But Martyn Williams handed the Maori the initiative when he awarded Hill three points for slowing the ball down deliberately.
Jones missed a chance to cut the deficit with a wayward penalty attempt and he suffered another setback soon after when he collided with a Maori shoulder and went off with blood pouring from his face, to be replaced briefly by Ronan O'Gara.
As half-time approached, the Lions began to assert some territorial authority and a Maori indiscretion handed Jones three points.
Two minutes into the second half Spencer came on in his last match for the New Zealand Maori.
The Northampton-bound star inspired a Maori insurgency and they poured forward, pounding the Lions defence deep in their 22 and spurning two kickable penalties.
With the Lions under pressure a third penalty soon came the Maori way and McAlister took the three points.
The Maori were fired up and surged again, setting up MacDonald for the first try of the game after good work from Spencer.
McAlister converted for 16-6 and soon added another penalty as the Lions became ragged and flustered.
With the game disappearing, the Lions finally exerted some pressure and manufactured a try for captain O'Driscoll after a solid rolling maul on the line.
Jones converted but the Lions had left themselves too much ground to make up and the hooter sparked the Maori celebrations.