ORIENT must turn this deficit around after a disappointing first half which means the club face elimination from the play-off chase, with Bournemouth up in their match.
Orient's play-off dream was rocked by Aaron Cresswell's stunning strike, on eight minutes. He unleashed a fizzing drive from 35 yards with his powder-keg boot to leave keeper Jamie Jones grasping at thin air.
No Orient player chased him down when the ball fell to him from Jonathan Téhuoé's clearing header from a corner, but few foresaw that goal from out of the blue.
Then Matt Spring was robbed by Robbie Weir on the stroke of half time and Adam McGurk went straight through on goal. He placed his shot nicely beyond the reach of Jones to strike a blow against fast-fading play-off hopes.
Tranmere had two chances and took each of them with aplomb.
Possession was not problem for the hosts after the shock goal, but turning it into chances was. Dean Cox carved out space for himself a couple of times but his shots went high and wide. Téhoué was doing a lot of running to scant effect, while Harry Kane was forced to often drop deep in pursuit of some possession.
The best chance yet was produced by Cox's pass across the penalty box on 33 minutes, but Téhoué was too slow to meet it with a shot. More of that sort of penetration is required during the second half because Orient played too much in front of the massed ranks of white shirts.
Rovers keeper Tony Warner has not been tested by a single on-target shot from Orient. But Tranmere have threatened little, apart from their goals. Jamie Jones has had a quiet time in goal without much to do except pluck the ball from the net after Cresswell's opener.
Teen prospect Dale Jennings has been a fringe figure, with Terrell Forbes and Adam Barrett in control of Orient's final third. But Orient have been punished severely and have to up the tempo urgently.
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