The hosts, who had lost their three previous friendlies, went ahead in the 12th minute when Blerim Dzemaili sent a looping header against the underside of the crossbar before the ball hit Namasco on the back and went into the net.
Switzerland experimented with Steve von Bergen and Fabian Schaer at the centre of the defence as coach Vladimir Petkovic continued his search for a reliable back line but they still looked vulnerable.
The Swiss, who face Albania, Romania and hosts France in Group A of this month's European Championship, created a flurry of chances early in the second half and were repeatedly thwarted by Namasco.
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The home team were stunned when Radu Ginsari equalised for Moldova in the 69th minute with a viciously dipping shot from 25 metres that caught goalkeeper Roman Buerki off his guard.
Forward Ahmed Mehmedi, who scored only two Bundesliga goals for Bayer Leverkusen this season, then spared Switzerland's blushes when he fired the winner from close range six minutes later.
(Writing by Brian Homewood; Editing by Tony Jimenez)
