Half-time: Sheff Wed 1 QPR 0
QPR trail at the break and are down to 10 men after Richard Dunne was sent off for conceding a penalty.
The veteran centre-back took down Leon Best as the striker surged through the channel but appeared to be heading away from goal at a tight angle.
Referee Paul Tierney viewed it as a clear goalscoring opportunity and sent-off Dunne, with Chris Maguire converting the penalty.
As QPR tried desperately to reorganise their short-staffed defence, Wednesday had a chance to double their lead but Maguire headed wide.
And on the stroke of half-time, Brian Murphy – between the posts for Rangers in the absence of the injured Rob Green – made an outstanding save to keep out Atdhe Nuhiu’s bullet header and keep his side in the game.
Rangers had begun well, dominating possession, but without creating a clear-cut chance.
Karl Henry blazed over while Ravel Morrison’s effort through a pack of players was comfortable for Wednesday keeper Damian Martinez.
Murphy had been untested for the first half hour, until the penalty, but he came good late in the half to ensure the deficit is only one goal.
QPR: Murphy, Onuoha, Dunne, Hill, Hughes, Hoilett, Barton, Henry, O’Neil, Morrison, Zamora.
Subs: Lennox, Carroll, Keane, Yun, Kranjcar, Maiga, Benayoun.
Follow West London Sport on Twitter