Michel Salgado, left, made a vital late block to keep Arsenal at bay
By Les Roopanarine
Arsenal's Premier League title aspirations suffered a significant setback as 10-man Blackburn battled their way to a deserved point.
The Gunners' best moment came late on, when Nicklas Bendtner had a shot blocked on the line by Michel Salgado.
By then, Blackburn had been reduced to 10 men following Steven Nzonzi's two-footed challenge on Laurent Koscielny.
Martin Olsson earlier went close with a speculative effort that was fumbled by Arsenal keeper Manuel Almunia.
Blackburn grew in belief after a shaky start - and their point owed much to a solid display from keeper Paul Robinson - but this was a distinctly laboured performance from Arsenal.
On a day when Manchester United overturned a two-goal deficit at Upton Park to cement their place at the Premier League summit, the Gunners could ill afford to slip up.
But falter they did and, as a consequence, they now find themselves seven points behind United - albeit with a game in hand - and contemplating the very real possibility of a sixth successive season without silverware.
These are not the only statistics that will cause Gunners boss Arsene Wenger discomfort.
Wenger gives damning verdict on draw
This was his side's third successive league draw and it came not only against a team with the worst defensive record away from home in the entire division, but with captain Cesc Fabregas watching the first 58 minutes from the bench.
Yet perhaps the most troubling aspect for Wenger will be the manner in which his team's conviction seemed to slowly dissipate after a promising opening, belatedly returning only once Nzonzi's dismissal had handed them the numerical advantage.
Blackburn's ambitions were initially limited to keeping the hosts at bay and barely five minutes had passed before Arsenal set up camp deep in enemy territory.
As Rovers backed off, Alex Song and Theo Walcott - both returning from injury - were soon causing anxious moments in the visiting defence.
Walcott went the closer of the two, forcing a sharp near-post save from Robinson, and for a time it looked like the visitors might be overrun.
Robinson's services were required again soon afterwards, with Ryan Nelsen almost putting through his own net as Arsenal revelled in the space they were afforded. But for all their possession, Wenger's side could not force a breakthrough.
Before long, Blackburn boss Steve Kean was barking orders from the touchline, urging his players to put more pressure on the ball.
Kean lauds 'tremendous' Blackburn
Olsson may have interpreted his manager's instructions a little too literally, for moments later he was involved in a crunching challenge with opposing full-back Bacary Sagna.
When Samir Nasri subsequently headed over under pressure from Ryan Nelsen, receiving a knock on the side of his head which produced immediate swelling, the physical intensity was ramped up a notch further.
And as Blackburn's appetite for the contest increased, so too did their threat on the counter-attack.
They received further encouragement when the defensive fragility that has undermined Arsenal's campaign in recent weeks once again reared its head.
Not for the first time, the chief culprit was error-prone keeper Almunia.
When Olsson tried his luck with a speculative effort that bounced off Almunia's hands before spinning wide, the home support - who had earlier greeted a successful catch by the Spaniard with ironic cheers - let out a collective groan of dismay.
The keeper's performance came under further scrutiny late in the first half when he failed to make contact with an upfield punt from Robinson, allowing an Nzonzi header to trickle just wide of Arsenal's unprotected goal.
By then, the home side had squandered further chances, the most notable of which came when Nasri squared for Jack Wilshere, who should have done better than send a mistimed shot wide from eight yards.
Koscielny later forced another sharp save from Robinson with a close-range header from Nasri's corner but not even the return of Fabregas from injury could rouse the home side from their torpor.
The catalyst instead was Nzonzi, who went in on Koscielny with studs raised and received a straight red card from referee Phil Dowd for his troubles.
Within minutes, a majestic exchange between Van Persie and Wilshere carved open the Blackburn defence to present substitute Marouane Chamakh with a clear chance but Olsson blocked magnificently.
Salgado then denied Bendtner on the line and, as Arsenal's afternoon descended into frustration, it became increasingly clear that the day's real winners would be Manchester United.
Arsenal manager Arsene Wenger:
"We had a bad performance today. You don't get away with that kind of performance against a Blackburn side who defended well.
"We had no change of pace, no penetration, our rhythm of passing was too slow - exactly how we don't want to play.
"It's disappointing, and I'm really concerned about the level of our performance today.
"Players have come back from international duty and they're not sharp - half of the team has not recovered."
Blackburn boss Steve Kean:
"We're delighted. We showed desire, commitment and togetherness, but we've been showing those qualities for a number of games.
"Going down to 10 men, everybody has to do their own job - and they did - I thought we were tremendous.
"We've got a bit of momentum and that's going to be key going into the last seven games."
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