Lewis Montrose's clinical strike midway through the first half proved decisive as Gillingham clinched a winning 1-0 start to the new season.
The Gills' victory was well-deserved although they were forced to endure a nervous last 10 minutes after substitute Luke Rooney was given a straight red card following a rash challenge on Brian Smikle.
Chris Whelpdale went close for the home side after cutting in from the right-hand side and curling his drive just over the bar. And they finally went ahead after 26 minutes, Montrose latching on to Jack Payne's deflected shot to drill home.
The home side almost extended their lead four minutes after the restart when Whelpdale's effort wrong-footed Brown, forcing him to scramble to push the ball past the post.
Cheltenham struggled to create chances but did almost find an equaliser after 57 minutes through Danny Andrew, whose curling free-kick whistled just wide of Ross Flitney's left-hand corner.
And the visitors were still unable to make a breakthrough, despite Rooney being shown his marching orders after 83 minutes.
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