From empty seats to flares and drums: how Arsenal fans have turned from fragile to ferocious at the crucial mo

With the smoke of flares in their nostrils, the sound of a pounding drum in their ears and the sight of thousands of Arsenal supporters on the streets outside the Emirates Stadium, the build-up to the Champions League semi-final was a sensory experience unlike anything Mikel Arteta and his players had ever seen before at a home game.