Sheffield Wednesday completed their first league double over arch-rivals Sheffield United in 95 years thanks to a wonderful first-half strike from Marcus Tudgay.
Tudgay let fly from 25 yards with a thunderbolt which arrowed into Blades' goalkeeper Paddy Kenny's top right-hand top corner in the 29th minute of a typically explosive 123rd Steel City derby.
Arturo Lupoli had earlier made a fine start to life as a Blade by heading an equaliser just four minutes into his Sheffield United debut to cancel out Tommy Spurr's stunning opener - scored with barely 60 seconds on the clock.
The Owls' win was only their second in nine league games and third away from home all season, but it required a superb save in the 91st minute from goalkeeper Lee Grant, who tipped Billy Sharp's shot on the turn over the crossbar.
The Blades are still in the thick of the promotion race, this was only their third defeat in 13 league matches, but the blue and white half of Sheffield will be crowing about this victory for years to come.
Inside the first minute Owls midfielder Michael Gray, on loan from Wolves, weaved his way into the penalty area and pulled the ball back for the unmarked Spurr to slam home the opening goal for the visitors.
But within four minutes the Blades were level. Greg Halford's long throw-in arced its way to the six-yard box and Lupoli - surrounded by Owls defenders - somehow managed to get his head to the ball and steer it home via the crossbar.
But Wednesday regained the lead in spectacular fashion in the 29th minute. Owls striker Tudgay found himself in space 30 yards from goal and set himself up to launch his rocket into the top corner for the visitors' second.
The Owls almost doubled their advantage five minutes after the restart. Tudgay headed on a throw-in and big striker Leon Clarke's volley from 10 yards smashed back off the post.
Sharp almost snatched an equaliser with a smart turn and shot in the dying moments, but Grant flung himself at the ball to turn it over for a corner and Wednesday were left to celebrate a famous victory.
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