Shane Long grabbed his first league goal since April as Reading carried their FA Cup form into the Coca-Cola Championship with a vital 1-0 win over Barnsley.
The Republic of Ireland striker took advantage of a fumble from Barnsley goalkeeper Luke Steele to poke home.
Former chief scout McDermott, who was confirmed in the job full-time on Wednesday, said: "I just wanted to get it done. It is important to the players, to the supporters and to the staff.
"We needed to bring stability to the situation. This is just what we needed. We showed courage and spirit, although 1-0 is always a bit hairy towards the end of the game.
"In the past things have happened when were leading 1-0, but the important thing about this result is that we got all three points."