Steel City derby: O'Grady recalls his match-winner the last time Sheffield Wednesday and Sheffield United clashed

For the striker - who is one of a select few in recent years to have played for both Wednesday and United - was hauled off for a routine drugs test after netting the Hillsborough winner on February 26, 2012.

It not only earned the Owls three points, but was a pivotal moment in both clubs’ fortunes that season.

Wednesday embarked on a 14-game unbeaten run which eventually overhauled the Blades to clinch automatic promotion.

It took United five long years to join their city rivals in the Championship, and Sunday will be the first time the city rivals have met since O’Grady’s winner.

“It seems a while ago, I have been to a good few clubs since,” said O’Grady, who went on to play for both Barnsley and the Blades – the latter on loan in 2014 – before joining Chesterfield in the summer.

“But I can remember being up against Harry Maguire.”

The key moment came when O’Grady, now 31, headed in Lewis Buxton’s cross beyond a helpless Steve Simonsen.

“The goal was a bit surreal, the ball went out wide, I got the header, then everyone was running up to the manager - led by myself,” he recalled.

“From that point it’s just a blur, I cannot remember the rest of the game.

“After the game I was hauled off for a routine drugs test, so I couldn’t even celebrate.”

If United had won at Hillsborough that day, they would have gone eight points clear of the Owls.

Victory for the hosts was not enough to save manager Gary Megson’s job, Dave Jones arriving to guide the Owls to promotion within a week of that derby win.

O’Grady said: “The win was a pivotal moment, it’s those fine lines in football.

“If my goal hadn’t had gone in, and we hadn’t got the win, who knows what would have happened.

Sheffield United were stuck in League One for years.

“It was important and I am glad to have been part of the derby, but also very special to have scored that goal because it spurred things on.”

O’Grady - who netted once in four games for the Blades in his one-month loan spell from Brighton in 2014 - is delighted to see both Sheffield clubs doing well in the Championship.

“When I was at United, they were still in League One, so still trying to scramble to get out,” he said.

“Whereas, Wednesday became comfortable in the Championship and are still there.

“United will have different pressures now, you are not expected to beat teams every week.

“United are on an even keel now, while Wednesday have got financial backing behind them. It’s good times for the city, both clubs doing well, and it’s good to see.”

O’Grady played against the Owls this season for Chesterfield in the League Cup, Wednesday winning 4-1 at Hillsborough.

Strikers Gary Hooper and Steve Fletcher netted that day, and O’Grady is tipping the Owls to win on Sunday if they can replicate that level of performance.

He said: “If Wednesday can play to their potential on Sunday, they will get the result.

“But it’s just a case which individual can get the best out of themselves on the day, for each team.

“I have got to say Wednesday to win, they mean a hell of a lot to me.

“It will be good to watch, and hopefully there will be a similar result as last time.

“I am looking forward to watching the game on TV with my children.”