The visitors go striding on after a battling performance that was roared on by nearly 1,000 travelling fans.
It was the sternest test Notts have faced in the competition in which they had earlier disposed of Crystal Palace, Middlesbrough and Southampton.
Wycombe started at a high tempo and carried the greater threat for much of the first half.
They were held at bay not least because of two outstanding saves by County's young Irish goalkeeper Saul Deeney.
It therefore seemed very cruel on him when he was to blame for Wycombe's soft goal which ultimately won the tie.
Ex-Notts man Stefan Oakes hit a free-kick into the penalty area which was not adequately dealt with. Deeney pushed the first shot away only for Jermaine Easter to pounce on the loose ball and drive it over the line.
It had taken Notts over half an hour to offer a serious threat to the Wycombe goal. Then Junior Mendes blazed over from six yards and Ricardo Batista saved with his legs to deny Mike Edwards.
After Wycombe's goal, Notts County needed to step up a gear and Edwards almost brought them level with a flying header from ten yards which Batista saved acrobatically.
As Notts continued to press forward, Wycombe remained dangerous on breakaways and veteran Tommy Mooney should have doubled their lead and settled the outcome. However, Deeney blocked his effort when all seemed lost to atone for his earlier error.
Notts offered more menace when bringing Dan Martin off the bench to replace Matt Somner.
With an eye for goal Martin drove one effort just wide of Batista's right-hand upright before drilling in a similar shot in the next attack but this time Batista got down well to turn it round the same upright.
Even in stoppage time Notts were still hunting an equaliser and forced both a corner and a free kick but, to the joy of the large contingent of travelling fans, Wycombe held firm.