
Banel struck the only goal of the game in the 22nd minute when he ran from the edge of his own box to the other end of the pitch to score a goal of the season contender.
Derby were made to sweat by Oxford, who are struggling at the other end of the table, with Mark Harris squandering a good chance while Sam Szmodics made a super tackle to deny Myles Peart-Harris.
But Eustace's side secured all three points which keeps them on the coattails of the top six ahead of this afternoon's fixtures.
Asked for his assessment of the game, Eustace said: "Brilliant win, against a really difficult opponent.
"They make it very difficult for you with a 5-4-1 formation and it's hard to break down.
"But I thought we played some really good football. It could have been better in the final third, but overall I am delighted with the three points.
"Oxford have only had two defeats in 10 and in those kind of games you need that bit of magic, that moment of quality and Jaydon certainly brought that.
"We got into some really good areas and the final pass wasn't good enough. And when he was going through, I wondered whether it was the right thing to do (go on his own) but obviously when it hits the back of the net, he certainly made the right decision."
Banel now has two goals for the season and asked about his contribution having moved to the club on loan from Burnley, he added: "He's got to be a big player now for us because we haven't got many players left.
"He's stood up today. I thought it was a great learning experience for him away at Southampton last week, and he's come back firing with the winning goal today.
"His work rate was very good. I'm delighted that there's been good progression there."