The gaffer spoke after our 1-0 victory over Wycombe Wanderers at Adams Park in Sky Bet League One.
A late header from substitute Slobodan Tedic sent the Reds back to Oakwell with all three points in a tightly-contested affair on Saturday afternoon.
Duff said despite the performance not being up to scratch in large spells, his side showed the versatility at their disposal.
"It's a brilliant moment for him (Tedic)," he opened. "It wasn't a great game, we weren't brilliant. I think we've shown a different side to us today. We've been free-flowing and free-scoring recently, we weren't at out best today. We didn't use the ball well enough. But, the growth from the group; the resilience and spirit."
The winning goal was Tedic's account opener for the Reds, connecting powerfully from a Luke Thomas cross on the left.
Our Head Coach stressed how the Serbian had earned his goal and the feelings that come with such a moment.
"I talk about it all the time, in terms of hard work paying you back. There'll be some brilliant pictures, I'm really pleased for him. He's worked ever so hard for that."
It's a big one up next - we welcome South Yorkshire neighbours Sheffield Wednesday on Tuesday under the lights at Oakwell.
There are limited tickets left for the clash - secure your place by clicking the banner below for what promises to be a special occasion!