Captain Arshavin controls the ball
The young Gunners, skippered by Andrei Arshavin who cannot play in Europe, again showed their potential as a brace from Nicklas Bendtner - his first after a blunder from England keeper David James - and a clinical second-half strike by Mexican Carlos Vela sealed a comfortable 3-0 victory.
Pompey, whose best spell came just after the restart, should have enough points on the board to be safe from the drop, while the Gunners head into their clash with United secure in the knowledge of another top four finish following a 21-match unbeaten league run.
Theo Walcott, Bacary Sagna and Alex Song - who dropped back to the centre of defence - were the only survivors from Tuesday night's 1-0 defeat at Old Trafford.'
Young Polish keeper Lukasz Fabianski - whose had a nightmare display in the FA Cup semi-final against Chelsea at Wembley - was given an early test when Peter Crouch's knockdown was drilled goalwards by Hayden Mullins, but he was down quickly to make a comfortable save.
On 10 minutes, Vela tried his luck from 20 yards, only to send the ball high over the crossbar.
It was no surprise when Arsenal took the lead.
A corner, in the 13th minute, was only half-cleared, and the ball dropped back out to Arshavin on the left.
His deep cross was met at the far post by Bendtner, whose downward header was spilled by James and rolled over the line.
The Gunners' fans at the far end mockingly chanted "England's number one" - with their regular keeper Almunia having seen his cause for international recognition through residency championed by Wenger.
It should have been 2-0 when Emmanuel Eboue raced into the left side of the penalty area and pulled the ball back for Vela.
However, the Mexican delayed the shot, which allowed Hermann Hreidarsson to make a superb recovery block.
Pompey almost snatched an equaliser when Crouch played a one-two with Belhadj on the edge of the area, only to stab his shot just wide of the far post.
Arsenal were awarded a penalty when Arshavin cut through the right side of the area and was tripped by Sean Davis after 41 minutes.
Bendtner scores through penalty
Pompey were less than impressed, claiming Davis had won the ball, with captain Sol Campbell, the former Arsenal defender, booked for dissent.
Although James went the right way, he could not keep out Bendtner's spot kick into the far corner.
Portsmouth came out in determined mood at the start of the second half.
Substitute John Utaka had a great chance to get a goal back, but dragged his shot wide from 12 yards.
Pompey continued to press, with Crouch the next man to fire off target from a decent position before Fabianski pushed away a 20-yard drive from Kanu, sent on for the second half to face his old club.
Somehow the ball stayed out when Utaka got to a chip into the area ahead of Fabianski as the home side saw another chance wasted.
It proved costly as Arsenal made it 3-0 on 56 minutes.
The ball broke for Vela on the left side of the Pompey area after Arshavin's shot was blocked by Hayden Mullins.
Vela celebrates his goal
The Mexican forward showed Pompey how to finish with a low strike into the far corner.
With the job done, Walcott was taken off for the final 25 minutes as Amaury Bischoff made his Premier League debut.
Bendtner, on a hat-trick, blazed over from 25 yards when a better option would have been the pass out to Sagna on the overlap.
James went some way to redeem himself with a fine one-handed save at the near post to deny Vela, before Bendtner was replaced by 19-year-old Fran Merida.
Things got worse for the home side with 12 minutes left when Noe Pamarot was sent off as last man for hauling down Arshavin on the edge of the area. Aaron Ramsey's free-kick struck the wall.
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