Paul Heckingbottom says an outstanding training ground performance was behind his surprise selection on Saturday.
The former Sunderland defender left Tom Bradshaw and Ryan Hedges, his two top scorers this season, on the bench and handed a start to Ike Ugbo.
The 18-year-old Chelsea loanee responded by opening the scoring, as well as laying on the assist for the third goal.
Heckingbottom said: “I was pleased with him. We had a training game and he scored four the other day. He showed his qualities today and his challenge is doing that in the Championship this season.
The Barnsley boss also moved away from his normal tactical set-up this season, starting with a 4-3-3 system.
The hosts struggled in the opening period of the game but cut Sunderland open on the counter-attack and were rarely troubled defensively in the second half.
“The most pleasing thing about the win was the storm we weathered at the beginning. A lot of it was our own doing and things we were getting wrong," Heckingbottom said.
“But we defended our box really well, made blocks and tackles when we had to and didn’t panic, which was the main thing.”