Lewes have seven games left to avoid relegation from National League division two.
A 2-1 defeat away to Indian Gymkhana left Lewes two points above the relegation play-off spot.
Lewes have still got to play the two teams below them but they must start scoring goals if they are to get out of trouble.
That was the problem on Sunday as Lewes enjoyed more possession and created a number of chances without being able to make them count.
Tejinder Hanspal proved the value of a proven goalscorer with two excellent first-half goals.
They sandwiched a reply from skipper Will Champness from a well-worked short corner routine.
Lewes had three more short corners before half time and another six in the second half but they were unable to take advantage of them.
Carl Wright had two good chances, as well as being denied what looked a clear penalty flick, and Nick van Tromp also went close but the skilful hosts held on.
East Grinstead also suffered a disappointing weekend as they went down 1-0 away to Hounslow and Ealing.
The late withdrawals of Matt McNeill, Duncan Howarth and David Litchfield did not help Grinstead who were beaten by a goal from Daniel Lloyd James on 32 minutes.
Grinstead had a chance to level in the second half when Steve Edmonds' shot was stopped on the line by a defender's foot but Ben Payne's weak penalty flick was well saved.
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