32-year-old Chris Wood gave Forest the lead early in the second half, with Noni Madueke quick to respond for the blues, making it 1-1.
Defenders Cucurella and Wesley Fofana were shown their fifth yellows of the season.
Despite now facing a £25,000 fine after picking up six yellows in the game, Blues manager Enzo Maresca says his players will not loose their heads.