But Kris Commons, in his first appearance since October, equalised just three minutes later to take the tie back to Pride Park.
"When you're on top you have to have to take your chances and I was slightly disappointed we didn't," said Jackett. "But we're in the hat and another home draw would be terrific. We'd love to have a big team at The Den, but we've got to get past Derby first.
"We're looking forward to the replay and we're not going to go there and be overwhelmed.
"They've got some good players and some big names but we competed well and will do the same up at Derby."