Lewes slipped into the Ryman Premier League relegation zone after sliding to a 2-0 defeat away at a wet Thurrock.
Despite a good start, with first half chances falling to Steve Brinkhurst, Nathan Crabb and Chris Breach, the Rooks found themselves trailing at the break when Shamir Mulling headed in at the far post.
And the visitors were second best throughout a second half played in torrential rain. And the game was up when Thurrock doubled their advantage on 74 minutes through the excellent Lewis Perkins, who smashed a sensational shot home from 30 yards.
Lewes will hope to claim the win that moves them up the table when they take on Wealdstone at home tomorrow (Bank Holiday Monday) in a 12.30pm kick off.