Lee fielded a virtual reserve side, making nine changes in his starting line-up from the team which drew with Tottenham on Sunday.
But he said: "I picked a team which I thought would win the match.
"Of course, I'm aware I'm under pressure - most managers are under pressure. But I never go to any match prepared to lose it, and it will be the same at Derby on Saturday. This result will give us a boost.
"I used the squad tonight, and our lads did well. It was a great story for Stelios, who has just come back after a hernia operation. He has a nice habit of scoring vital goals."