Sheffield Wednesday have opened up a surprise 2-0 lead over Arsenal in the first half of their fourth-round League Cup tie at Hillsborough.

The visitors were dealt an early blow when Alex Oxlade-Chamberlain was forced off less than five minutes into the encounter with an apparent hamstring problem, resulting in Theo Walcott coming off the bench.

Arsenal did get the first sight of goal, though, as Olivier Giroud burst forward to control a high ball into the area, but the Frenchman was ruled offside before he could get his shot away.

The Gunners were dealt a further injury blow soon after as Walcott was forced off with a calf problem, bringing 17-year-old Ismael Bennacer on.

Despite Arsenal dominating possession for much of the opening 25 minutes, it was the hosts who opened the scoring just short of the half-hour mark when Ross Wallace drove the ball into the bottom corner after hitting it first time following a through-ball from Daniel Pudil.

The Scot could have added his second soon after as he attempted to get the better of Petr Cech again from a free kick just outside the box, but his curling finish just missed the target.

The Owls did double their advantage before the break though, taking a corner short to set up Lucas Joao for a header at the far post following a cross from Wallace, leaving the home side in control at the interval.