Seven minutes was all it took for the hard work that the Reds put in at the weekend to be forgotten as Ross McCormack scored the first of a 28-minute hat-trick.
Henri Lansbury's strikes either side of half-time gave Forest some hope but first-team coach Brian Eastick admitted afterwards: "We lost the game in the first 20 minutes.
"If you give the quality of McCormack that much space and time he will punish you."
Home boss Kit Symons said: "In the second half Forest had a right go but we were resolute, we stood up and were counted.
"They were putting a lot of balls into our box, there was always that danger that something would fall for them but I was pleased with the way we defended overall."