Sheffield Wednesday boss Carlos Carvalhal says Sheffield United's blistering start to the Steel City derby at Hillsborough added a nervousness to his side that the Owls failed to deal with.
Wednesday were 2-0 down after just 15 minutes after goals from John Fleck and Leon Clarke.
The home side did manage to pull one back before the break through Gary Hooper and then early in the second half with Wednesday's tails up substitute Lucas Joao equalised.
However another sub, Mark Duffy immediately pulled United back into the lead with a great strike, helped in no small part by some awful Wednesday defending.
Clarke added his second to pile more misery on the Owls who struggled amid the tense derby atmosphere.
"It was a game with very high emotions and in this kind of environment if you start losing after two minutes it makes us more nervous," he said.
"We were nervous because of their early goal and we did mistakes that we don't usually do. The beginning of the game gave us instability.
"At 2-2 I thought most of the people in the stadium and watching on television thought we would win but Sheffield United got the goal. It was very hard for us. We never usually make these mistakes."
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