And it was not long before the curse of Southgate struck the Gunners again when former player Aliadiere guided Tuncay's half-volleyed cross from the left high into the Arsenal net.
The strike came against the run of play, although Arsenal were guilty of not making the most of their possession.
The north London giants looked like a team under pressure and their state of mind was probably not helped after learning of the earlier wins for title rivals Chelsea and United, who leapfrogged Arsenal.
Midfielders Alexander Hleb and Cesc Fabregas were busy in the middle but their energy was matched by Boro's midfield, with George Boateng and Gary O'Neil particularly outstanding.
And up front, Arsenal's attack found it difficult to break down a stubborn and regimented defence led by German Robert Huth.
The Gunners were restricted to just a few sighters in the first half - Emmanuel Adebayor failed to get a good connection on Fabregas' punt downfield and then strike partner Robin van Persie, who looked rusty, screwed his 12-yard shot wide.
Their best opportunity in the opening 45 minutes fell to Emmanuel Eboue, but his deflected shot from close range bounced off the arms off Mark Schwarzer.
Wenger brought on Theo Walcott and Nicklas Bendtner to inject some energy into the laboured attack, but even their youthful exuberance was stifled by Boro.
Fabregas should have brought the Gunners level but had a shot brilliantly blocked by Schwarzer and then struck the post with a downwards header.
But he did have a hand in the equaliser when his right-wing corner found the head of Toure who powered in the ball past a crowd of players.
In the closing moments, Arsenal frantically looked for a winner while Boro defended like warriors, although Southgate's good day was tarnished by the red card shown to Mido.
The Egypt striker, on as a substitute, was given his marching orders by Mark Halsey after his boot met the head of Clichy, who had to be stretchered off with the bloody injury.
• Middlesbrough manager Gareth Southgate:
"Arsenal are a fantastic team but the character my players have shown this week is incredible.
"To give that sort of effort and commitment was brilliant.
"They have played ever so well, scored a fantastic goal and just dug in and managed to find the energy to hang on."
• Arsenal manager Arsene Wenger:
"The result is disappointing and I don't think we got the result we deserved.
"We played against a side who played very deep and defended very well.
"It doesn't go for us at the moment but we have to go through a patch like that and show our strengths."
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