By Jamie Spencer Barcelona failed to reach the Copa del Rey semi-finals for the third time in five seasons on Wednesday night, falling to a 4-2 extra-time defeat to Athletic Club in the last eight. The home side’s winner in the second minute of stoppage time at the end of the first half of extra-time, scored by substitute Inaki Williams, proved decisive after a four-goal thriller had been played out over the original 90 minutes. As Barca pushed for a last-ditch equaliser to force a penalty shootout, Nico Williams – a player heavily linked with a move to Catalonia, sealed it in Athletic’s favou…