Sheffield United came away from Pride Park with all three points after Matthew Kilgallon's second half goal was enough to seperate the teams.
The Blades made one change with James Harper making his debut in the place of Ched Evans, who has spent the week away on International duty, and Darius Henderson played as the lone striker with Ward and Treacy switching wings midway.
The Blades deserved the victory, and were unlucky not to have won by a bigger margain. Jamie Ward's injury time chance, would have put a Blades shaped cherry on the cake.
Nigel Clough's side did have their chances, Gary Teale early on, as well as Pearson, who just put Green's cross over the bar.
Debutant Harper slotted straight into the midfield, alongside Montgomery and Quinn, but sat in a holding role, allowing Quinn the most freedom of the trio.
Henderson caused problems up front, but went into the book for dissent and had a number of opportunities that he failed to take. However, it was his link play with Treacy that caught most Blades fans eye, with the winger creating chances as well as taking them himself, but unfortunately without result.
Although, it was Treacy who would create the goal in the end. After Stephen Quinn was fouled, Treacy swung in a free kick and the ball ended up looping over Bywater and into the net courtesy of a melee of players. Kilgallon claimed the goal, but it appears it could have been Rob Hulse's first goal for United since his horrific leg break at Stamford Bridge.
The Derby County striker won't be too eager to claim it, so Kilgallon could be credited with his first goal of the season.
Ched Evans replaced Henderson with fifteen minutes to go, but was unable to add his name to the scoresheet. Jamie Ward could, and perhaps should have doubled the lead in stoppage time, rushing through behind the defence, but his effort didn't beat Bywater.
"We work on set-pieces and it is nice to see what we do on the training ground pay dividends."
"The only real difference between the sides was when their chance came, they took it.
"That is the fine line the Championship, and that is why they are one of the favourites to get out of this division.
"Frustration is the word in the dressing room at the moment and it is a defeat quite hard to take because there were only ten minutes to go when they scored and it gave us little time to bounce back.
"Sheffield United are a bench-mark because they were in the playoffs last season and have the favourites tag on them this year, and I think we gave a good account of ourselves.
"We matched them quite well and I think that is a positive we can take away from today's game although so soon after the final whistle it is hard to look at the positives."