Thierry Henry led Arsenal back to the top of the Premiership as they crushed Middlesbrough at Highbury.
Henry gave the Gunners the lead by slotting home a penalty after Patrick Vieira had been fouled by Ugo Ehiogu.
They doubled their lead when an Henry free-kick was sliced into his own net by Boro defender Franck Queudrue.
Robert Pires made it three and Freddie Ljungberg slotted home after Kanu's run, before Massimo Maccarone netted a late consolation penalty for Boro.
Arsenal got off to a flying start, keen to get back on top of the Premiership with champions Manchester United not playing until Sunday.
Jeremie Aliadiere - replacing Kanu in the Gunners attack - nearly opened the scoring after just 41 seconds, but he was denied by the legs of Mark Schwarzer.
And soon after Henry curled a right-foot shot from the edge of the box that Schwarzer did well to turn over the crossbar.
39 mins: Henry scores from the penalty spot
45 mins: Queudrue's own goal doubles Arsenal's lead
57 mins: Pires slots home
68 mins: Ljungberg converts Kanu's pass
86 mins: Maccarone scores a penalty for Boro
But Middlesbrough managed to weather the early storm, and Doriva tested Jens Lehmann with a vicious 30-yard strike that the German parried away to safety.
As the game swung from end-to-end Patrick Vieira fired wide from 25 yards, then the Frenchman had to be alert to cut out a cross from the right that was heading for George Boateng.
With 37 minutes gone, Arsenal finally got the breakthrough. Vieira surged into the box and was tripped by Ehiogu, Henry stepping up to convert from the spot.
In first-half stoppage time the hosts doubled their advantage. Henry curled in a testing free-kick from the left and Queudrue could only slice the ball into his own net.
Arsenal needed to score four goals to go back to the top of the table, and they came out after the break looking determined to add to their tally.
After Boudewijn Zenden sent a shot wide for Boro, the Gunners moved through the gears once again and Doriva did well to block a fierce Ljungberg volley.
Henry then burst away down the left and although Gareth Southgate managed to block his cross, the ball fell kindly for Pires who rammed it past Schwarzer.
Kanu, who came on for the injured Aliadiere at half-time, produced a piece of magic for Arsenal's fourth.
The skilful Nigerian went on a jinking run that ran the Boro rearguard ragged, and Swede Ljungberg was on hand to convert his pass past a bemused Schwarzer for his 50th goal for the club.
As Arsenal stepped off the accelerator Boro finally enjoyed some prolonged possession, and they looked keen to narrow the margin of defeat as Juninho's shot was blocked by Sol Campbell.
Four minutes from time they did grab a consolation, as Lehmann was adjudged to have brought down Maccarone in the area and the Italian slotted home the resulting penalty.
Arsenal: Lehmann, Lauren, Campbell, Cygan, Cole, Ljungberg (Parlour 72), Vieira, Silva, Pires (Edu 67), Henry, Aliadiere (Kanu 45).
Subs Not Used: Keown, Stack.
Middlesbrough: Schwarzer, Mills, Southgate, Ehiogu (Riggott 45), Queudrue, Job (Maccarone 62), Boateng, Downing, Doriva (Juninho Paulista 62), Zenden, Nemeth.
Subs Not Used: Parnaby, Jones.
Referee: A D'Urso (Essex).