The first half-hour was pretty turgid, with Arsenal being so frustrated by Hull that their traditional game went to pot, with passes going astray and a lack of urgency in front of goal.
Arsenal v Portsmouth previewArsenals Cesc Fabregas: Dont single me out for punishmentBoaz Myhill, in the Hull goal, had little to keep his hands warm until first-half stoppage time, when Denilson scored.
Without the injured Robin Van Persie in attack and Cesc Fabregas in midfield, Arsenal struggled to impose themselves on Hull, who have not won away in the league this season.
Abou Diaby had a shot deflected away for a corner, Samir Nasri shot tamely at Myhill and Eduardo curled one past the far post from the edge of the penalty area, but there was rarely a real threat, with Andrei Arshavin particularly disappointing.
Hull were content to soak up the pressure and attack on the break, with Stephen Hunt and Craig Fagan both going close.
Given the bad blood surrounding the corresponding fixture last season, it was not surprising that there was a hint of menace lurking under the surface and it erupted in the 43rd minute with a fracas that involved 21 players - the only absentee being William Gallas, who as Arsenal's captain would have been expected to intervene.
The trouble started after the award of a free-kick to Arsenal. As play stopped, Nasri took a sly kick at the ankle of Richard Garcia, who fell theatrically and prompted a violent reaction from his tream-mates. After much pushing and shoving, referee Steve Bennett booked Nasri and Hunt.
The resulting free-kick came to nothing, but the incident caused three minutes of stoppage time to be added, during which Arsenal opened the scoring.
They were awarded a soft free-kick when Diaby went down under a slight touch from Kamil Zayatte, and Denilson made no mistake when he curled a each of a free-kick over the defensive wall and past Myhill's grasp from 25 yards.
Protests about Nasri continued as the players left the field, and within eight minutes of the second-half starting. Hunt's cross was way above Fagan's head, but Mikaeel Silvestre tangled with the striker, who fell to ground. Contact was minimal, but referee Bennett mimed a shirt-pulling action as he pointed to the penalty spot.
Geovanni's body language was all wrong, however, as he ran up painfully slowly to take the kick, and the Brazilian's shot was easy for Manuel Almunia to save. Although the Spaniard could not hold the ball, the rebound was headed horribly wide of an open goal by Hunt as he followed up.
Six minutes later Hull were punished as Eduardo made it 2-0. The striker scored his first league goal since the opening day of the season, and it was as easy as they come, a simple tap-in from close range after good work on the left by Diaby, who exchanged passes with Alex Song before cutting the ball along the byline.
With time running out and the game over as a contest, Arsenal made it 3-0 in the 80th minute when the outstanding Diaby played a 1-2 with Arshavin on the edge of the penalty area and fired in a shot that Myhill got a hand to but could not stop. Game over.