It was a dream first half for Stevenage as they ripped Wednesday apart to lead 4-0 at the interval, while the visitors were reduced to 10 men in the closing stages when substitue Jermaine Johnson was sent off for violent conduct.
Craig Reid opened the scoring in the sixth minute when he pounced after Wednesday goalkeeper Richard O'Donnell had saved Ronnie Henry's initial shot.
Five minutes later it was 2-0 as John Mousinho fired an accurate low drive past O'Donnell and in the 17th minute Stevenage extended their lead as Michael Bostwick steadied himself before burying a shot which flew in off the post.
The fourth goal, eight minutes before the break, came when Lawrie Wilson was fortunate as his mis-directed effort somehow crept past the stunned O'Donnell.
Darius Charles rifled in the fifth in the 67th minute before Wednesday finally responded seven minutes later when Gary Madine tapped home a consolation, but it got worse for the Owls when Johnson was sent off in the dying minutes following an off-the-ball incident.