Two goals from Aaron Ramsey helped Arsenal to a 3-1 victory in a topsy-turvy encounter against Sunderland at the Stadium of Light.
With debutant Mesut Ozil pulling the strings, the visitors dominated the first half only for Sunderland to pull level and have two goals disallowed in between Ramsey's double in the second half.
The win puts Arsenal level on points with Tottenham and Liverpool, with the latter facing Swansea on Monday night.
Arsenal handed a start to record signing Ozil on his debut, while Bacary Sagna started at centre-back in place of Per Mertesacker. Ki-Sung Yeung made his debut for Sunderland, having been picked up from Swansea on loan at the end of the transfer window.
However, it was Ozil who made his mark almost immediately. Picked out on the left flank via a long ball, he killed the ball with a great first touch then drilled in a low cross which Olivier Giroud tucked home at the near post for his fifth goal of the season.
Sunderland were rocked, but responded through a spectacular effort from Diakite as he beat Giroud to a corner with a header that crashed off the bar with Wojciech Szczesny well beaten.
Ozil created the next chance, again having the vision to send Walcott though on goal, but Kieren Westwood stood his ground well to block. The same combination linked up again midway through the first half, but again Westwood was off his line well to thwart the danger.
Arsenal continued to dominate throughout the first half but the closest they came to extending their advantage came when Jack Wilshere's cross picked out Walcott, but his header could only find the side-netting. Walcott squandered another chance in first-half stoppage time, this time opting to shoot when he could have passed and Westwood again blocked, with Ozil denied on the follow-up.
Having dominated the first half, however, Arsenal found themselves level only three minutes after half-time. Sunderland winger Adam Johnson was tripped in the box by Laurent Koscielny, and Craig Gardner stepped up to slam the penalty beyond Szczesny.
Sunderland fans were on their feet again soon after as Steven Fletcher turned the ball home, but the Scotland international was comfortably offside, much to the relief of the travelling Arsenal support. Johnson then flashed a shot across the face of goal as the home side began to assert themselves.
It was therefore slightly against the run of play when Ramsey fired Arsenal back in front. The midfielder took Carl Jenkinson's pass and drilled a volley through Westwood and into the net on 67 minutes.
Sunderland felt further aggrieved three minutes later when they thought they had equalised through Jozy Altidore, but referee Martin Atkinson had already blown for a foul in Sunderland's favour when playing advantage would have seen the scores levelled.
As if to rub salt into the wound, Ramsey made it 3-1 soon after. The Welshman began the move by feeding Ozil, who then picked out Giroud, who in turn played in Ramsey with a first-time pass that was struck home with confidence for his fifth goal of the new campaign.
The frustration boiled over for Sunderland manager Paolo di Canio, who was sent to the stands in the closing stages.
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