Middlesbrough earned a shock win at Highbury to boost their hopes of survival and hand the Premiership title to Manchester United.
Two own-goals from Brazilians Edu and Silvinho and a strike from Hamilton Ricard put Arsenal's seemingly unstoppable drive for a Champions League place on hold.
Arsenal enjoyed endless possession but were out-thought by a stifling Boro side at an understandably subdued Highbury.
Even Venables would agree that if Arsenal had had a touch more fortune and finishing prowess, the title race would still be alive.
Arsenal had a number of chances to get their noses in front in the opening exchanges.
First Henry split the Middlesbrough defence with a neat ball to Kanu.
But the Nigerian's low shot was well blocked by Middlesbrough keeper Mark Schwarzer.
Henry then stole the ball in the midfield before sending an ambitious curling effort over the bar.
But it was Boro who took a shock lead in the 37th minute.
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In a rare venture into Gunners territory, Tony Adams' poor clearance fell to Dean Windass.
The former Bradford striker miscued his shot from 20 yards, but it struck the luckless Edu on the heel and slipped beyond the dive of David Seaman to squeeze just inside a post.
Arsenal threatened an immediate reply but Adams' header flew over the bar on 38 minutes.
Dean Gordon galloped down the left before whipping in a dangerous cross from the left and the full back's intended clearance shot past Seaman.
Refused to crack
Arsenal began the second half showing more purpose.
Kanu sent a powerful header wide, Silvinho had a great free-kick turned round the post and Henry had a shot on the turn well-blocked.
But whatever the Gunners threw at Venables' side, the Boro defence refused to crack.
And the game was put beyond doubt in the 58th minute when the Gunners were caught out again by a classic sucker-punch.
That ended any hopes Arsenal had of clinching this year's Premiership title and earning anything from this game.
Now the Gunners must pick themselves up for their crucial clash with Valencia next week, while Boro can bask in the glory of a rare victory at Highbury.
Arsenal: Seaman, Dixon, Keown, Adams, Silvinho, Pires, Vieira, Edu, Ljungberg, Henry, Kanu. Subs: Wiltord, Manninger, Parlour, Luzhny, Cole.
Middlesbrough: Schwarzer, Gavin, Ehiogu, Vickers, Karembeu, Okon, Ince, Windass, Gordon, Boksic, Ricard. Subs: Mustoe, Marinelli, Stamp, Crossley, Whelan.
Referee: P Durkin (Dorset)