Substitute Daniel Ceballos fired Arsenal into the FA Cup semi-finals with a stoppage-time goal that sealed a 2-1 win over Sheffield United at Bramall Lane.
John Lundstram had an early header ruled out for offside for Sheffield United, who went behind when Chris Basham fouled Alexandre Lacazette in the penalty area and Nicolas Pepe slotted home the penalty in the 23rd minute.
The game looked to be heading for extra time when David McGoldrick equalised in the 87th minute, hooking home a volley after Arsenal failed to clear a corner, but Ceballos popped up to slot home the winner.