Boss Jos Luhukay believes the Owls face "one of the best teams" in the Championship tonight.
Fourth-placed Middlesbrough travel to Hillsborough aiming to bounce back after their home defeat to Nottingham Forest before the international break.
Boro, managed by Tony Pulis, have lost just twice this term, conceding a meagre six goals.
Luhukay said: "Middlesbrough are one of the best teams in the league.
"They made the play-offs last year and are in a play-off position now. They're a fantastic team and have a very good coach.
"They're unbelievably strong in defence and offensively they have players who can make a difference. They're a good team, they have a good balance and a lot of experience.
"It will be a tough, interesting game for us.
"We have a lot of respect for them but most importantly my team has confidence, trust and belief in each other.
"We have not lost at home this season. We will do everything for a good result."
The Dutchman, who has revealed Fernando Forestieri faces a couple of weeks on the sidelines due to a hamstring problem he sustained against Bristol City, is under no illusions at the size of the task facing his Wednesday players as they look to maintain their unbeaten home record.
"They are a very physical and strong team but they also have very good tactical discipline when they don't have the ball," said Luhukay. "They don't give a lot of chances away.
"They have very quick players in the offensive transition. Players who can make a difference and that don't need a lot of chances to score.
"Of course, set pieces will be important.
"They have big players so we must be focused for every free kick or corner. Hopefully we can stop their quality.
"It will be a hard fight to come to a good result.
"We must have the passion and ambition. We are three points behind Middlesbrough. Hopefully we can play a good game and get a very good result."