It was, however, a fair result as Villa had been on top for long spells of the game despite after-the-match claims from manager Arsene Wenger that the Gunners had never been in trouble.
Three times Villa hit the woodwork as Arsenal were in danger of being destroyed. But they rode their luck to emerge with a good point.
The early turning point was when Denison took advantage of a Nigel Reo-Cocker mistake to give the Gunners a lead they hardly deserved.
Abou Diaby's goal four minutes into the second half was of the highest quality and seemingly sealed the three points for Arsenal, but a Gareth Barry penalty after 65 minutes put the match back into the boiling pot with Knight grabbing only his second goal for Villa in the closing stages.
Villa, on the back of a six-game unbeaten run, certainly made an electrifying start on a cold winter's night as they immediately pressurised the inconsistent Arsenal side but it was all to no avail.
An indication of Villa's early determination was shown when Ashley Young narrowly failed to make a connection with his head to a right-wing cross from
In the sixth minute a far from secure Arsenal had a real-let off when Steve Sidwell smashed his header against the crossbar following a right-wing corner.
Ominously very little was seen of Arsenal's attack which had been expected to exert pressure on the opposition's weakened defence which lacked the services of Martin Laursen and Carlos Cuellar.
Villa surprisingly maintained their blistering start and defender Luke Young moved up into the attack to crash a shot just over the bar.
With William Gallas struggling at the heart of Arsenal's defence and the midfield lacking the class for which Arsenal have been renowned, Villa dictated for long spells.
Skipper Manuel Almunia excelled with a save from Gabby Agbonlahor. However, the Gunners skipper could only parry the ball out to the on-rushing Sidwell and the attacking midfielder saw his shot deflected away for a corner.
The Gunners lacked the skill to dominate a game and their performance only confirmed that the former top-four clubs are no longer having it all their own way.
Only the woodwork saved Arsenal again in the 35th minute when Milner's effort was pushed onto the post by Almunia, while a long-range cross from Curtis Davies skidded off the crossbar.
Five minutes before the break Villa were rocked when Reo-Coker lost possession and the ball drifted into the path of Denison who hammered a low, raking shot past Brad Friedel - the first time the Villa keeper had been seriously tested.
There was no fluke about Diaby's goal four minutes into the second half though. He created the opening on the halfway line with a delicate reverse pass to Samir Nasri and then careered forward to take the return pass before firing home on the run past a helpless Friedel.
Robin van Persie smashed an effort against the post with Villa on the ropes which indicated the transformation which had previously taken place in a ten-minute spell either side of half-time.
But Villa were far from finished. The petulant Gallas brought down Agbonlahor inside the penalty area and Barry smashed home the 65th-minute spot-kick to set up an exciting finish.
Slack marking from a Reo-Coker free-kick enabled Knight to score with a low shot following a pass from Barry in the 90th minute to ensure the points were shared.