The Steel City rivalry is up there with one of the most fearsome in British football.
The two teams won't be in the same division next season after Sheffield United were promoted to the Premier League following a superb season under Chris Wilder.
Cross-city foes Wednesday, in a very sporting and surprise gesture, have congratulated the Blades on their achievement.
In a statement on their website, owner Dejphon Chansiri wrote: "Few things in life unite and divide opinion like football. But one thing at this stage of every season is undebatable and I would like to offer the warm congratulations of everyone at Sheffield Wednesday to everyone at our neighbours Sheffield United for their achievement of promotion.
Leeds United receive transfer boost, Swansea City and Aston Villa battle for striker as Crystal Palace target West Brom ace
"We may be rivals but we are friends of the same city that holds such unique tradition in the football world. Recognition in the Premier League can only benefit Sheffield and we wish United well, whilst promising our loyal supporters that we will be giving our absolute best to ensure Wednesday will be tasting the same success this time next year.
"We must also congratulate Norwich City on their promotion and offer our commiserations to Ipswich Town, Bolton Wanderers and Rotherham United. We wish you a speedy return to the Championship."
The response from Owls supporters has been something else.
Extremely sporting indeed.
Sheffield United plot striker transfer as Cardiff City star's future remains up in the air
