Injuries cast cloud over Arsenal's stroll into FA Cup last eight
Olivier Giroud and Theo Walcott netted braces as Arsenal eased through to the FA Cup quarter-finals, although the comprehensive victory at Hull looks to have come at a cost for Arsene Wenger's men.
Winning the competition for a third straight year looks to be the Gunners' most realistic shot at silverware, having fallen eight points behind surprise league leaders Leicester and requiring a huge turnaround to avoid being dumped out of the Champions League by Barcelona next week.
Wenger refused to pin all of his trophy aspirations on the FA Cup ahead of the trip to Hull, but will have no doubt been relieved to see Arsenal win this fifth-round replay 4-0 - albeit concerned that Per Mertesacker, Gabriel and Aaron Ramsey all limped off at the KC Stadium.
Giroud's first goals since January 13 were key to this victory, with the France striker hitting a brace the day after his partner gave birth to a baby boy.
The 29-year-old gleefully steered home a wayward David Meyler pass late in the first-half and then fired in a cross from Walcott, who added gloss to the scoreline by turning home coolly and then fizzing past Eldin Jakupovic late on.
It makes this the third straight season that Arsenal have knocked Hull out of the FA Cup, but concerns over Mertesacker, Gabriel and Ramsey will likely dominate the post-match talk.
Whether they will be ready for Sunday's hastily-arranged quarter-final with Watford is doubtful - unlike the result last night, which looked likely after Walcott steered home inside three minutes.
That goal was chalked off for offside but Arsenal continued to threaten, with Joel Campbell curling over at what was an atmosphere-free start.
The noise belatedly rose around the ground on the half-hour mark as Hull found the net during a penalty-box melee.
David Ospina produced a wonderful one-handed save to deny Meyler and threw his body in the way to deny Nick Powell, although the flag had already been raised by the time Ahmed Elmohamady eventually struck home.
Mertesacker limped off in the 33rd minute as the tie looked to perhaps be turning the hosts' way, only for Meyler's shocking decision five minutes before half-time to put Arsenal on their way.
The Republic of Ireland midfielder decided to direct the ball back to goalkeeper Jakupovic - a poor decision capitalised on by Giroud, rolling a shot past Hull's back-up goalkeeper.
It left Jakupovic - man of the match as the sides drew 0-0 at the Emirates - without much hope, as did the Kieran Gibbs effort that quickly followed, rattling the crossbar from 30 yards.
Alex Bruce came close with a header before half-time, but Arsenal returned from the break strongly and Jakupovic needed to be at his best to tip over a dipping Mohamed Elneny volley.
Mo Diame threatened in the air at the other end, but the visitors' injury worries worsened when Gabriel signalled to the bench his night was over.
Hull attempted to capitalise on the makeshift centre-back pairing of Calum Chambers and Nacho Monreal, with Powell striking wide and substitute Sone Aluko coming close, but Arsenal soon moved up a gear.
Walcott clipped a lovely ball for Giroud to fire home and, after the disappointment of seeing substitute Ramsey trudge off, provider turned scorer in the 77th minute.
Campbell was the architect, firing a lovely pass that Walcott controlled and turned home.
The England forward added another with two minutes remaining to wrap up a comprehensive victory.
HULL: Jakupovic, Maguire, Bruce, Davies, Elmohamady, Diamé, Huddlestone, Meyler (Aluko 58), Odubajo (Robertson 81), Powell, Diomande (Taylor 88).
Subs not used: Hernández, Livermore, Kuciak, Tymon.
ARSENAL: Ospina, Chambers, Mertesacker (Monreal 33), Gabriel (Ramsey 57, Reine Adelaide 73), Gibbs, Elneny, Flamini, Campbell, Iwobi, Walcott, Giroud.
Goals: Giroud 41, 71, Walcott 77, 88
Subs not used: Özil, Sánchez, Macey, Willock. Man of the match: Giroud
Match rating: 7/10 Ref: Mike Jones