Bothroyd returned earlier in the month from an unsuccessful loan spell at Sheffield Wednesday.
But the striker showed he has not lost his eye for a goal with his second-half header setting up a home fourth-round meeting with MK Dons.
He said: "Jay Bothroyd did well. He was written off. He's been at Sheffield Wednesday and not done very well.
"They sent him back and I thought I'd give him a go and see what he could do.
"He did well but then again, he played for England a couple of years ago under Fabio Capello."