Patrick Roberts, the subject of the chat on Saturday morning, scored his first goal since his January loan move from Manchester City as Derby twice fought back to avoid relegation and send Wednesday down.
Rooney said: “I spoke to him (Patrick Roberts) this morning. We were having breakfast and I went over and said to Patrick: 'You haven't scored a goal all season, so today cut inside on your left foot and whip it in the top corner!
“So for him to do it, it's great because I felt if we had that calmness there was a great opportunity for Tom Lawrence and Patrick to get into those pockets and cause problems.
“It was a crazy game and I think it's the story of our season but the important thing is that we stayed in the division.
“My message to the players at half-time was stay calm, don't panic, I felt we could hurt Sheffield Wednesday although I didn't think we would come out and score two goals so quickly.
“Then again, the story of the season, we concede two very sloppy goals but Martyn (Waghorn) comes up with the penalty, there was a lot of pressure on him to step up and take a great penalty."