John Mousinho came back to haunt former club Wycombe with a stunning second-half winner for 10-man Stevenage.
The midfielder, who left Adams Park last June, smashed in the winner two minutes after the restart and that proved enough to down the high-flying Chairboys.
Left-back Scott Laird was sent off for two bookable offences but Stevenage held out for a deserved win.
In the fifth minute Darius Charles fired woefully wide from 25 yards for the visitors before veteran winger Gareth Ainsworth smashed a shot from the edge of the box over the crossbar.
The first time a goalkeeper was called into action was in the added minutes of a dire first period when Laird's free-kick forced Nikki Bull into a brilliant save low down to his left.
But Boro were ahead two minutes after the restart when Mousinho let fly from 25 yards to beat Bull after Rob Sinclair's rampaging run forward.
Soon after more good work from Sinclair found Charles in the box but his shot was brilliantly saved by Bull.
Laird picked up his second yellow for a crude foul on Scott Rendell but despite the man advantage Wycombe failed to test Chris Day in the closing stages.
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