Olivier Giroud fired a first-half winner as Arsenal withstood a late Tottenham barrage to claim a crucial 1-0 win in the north London derby at the Emirates Stadium.
Tottenham threw everything they could at the Gunners in the second half but the home side held on to claim a valuable three points and a vital win.
Going into the game all the talk surrounded the transfer activity of the two north London rivals, but it was Arsenal, who are yet to spend a penny, who settled the quickest.
Two Santi Cazorla free-kicks went close early on but after bossing the opening 10 minutes, Tottenham settled into their stride and took hold of the game through their powerful midfield trio.
Andros Townsend was lively on the Spurs right-wing and tried his luck from range, but it was during the visitors best spell that the only goal of the game came.
With the ball on the right wing and with Spurs full-back Danny Rose too narrow, the superb Theo Walcott had room to move into after 23 minutes.
The Arsenal winger made his way into the box and with the Tottenham backline woefully out of shape, Giroud ghosted across his man to finish deftly past the impressive Hugo Lloris.
Spurs were rocking after conceding and Lloris was called into action on more than one occasion, but made it through to half-time with conceding further.
Andre Villas-Boas' side emerged the second half much the stronger, although a common theme emerged as they controlled possession without making any serious inroads.
Arsenal, without Jack Wilshere who came off through illness in the first half, were dangerous on the counter-attack and only a sublime tackle from Kyle Walker kept the scoreline at 1-0 late on in the second half.
Spurs, now with new record-signing Erik Lamela on the pitch, surged forward and caused a few scrambles in the Arsenal box, but Walker and Roberto Soldado couldn't get their shots away properly on separate occasions.
Indeed, it is an indication of Tottenham's lack of penetration that the only time Wojciech Szczesny was seriously called into action came courtesy of a deflected shot that had him scrambling.
In the end Arsenal held on, much to the delight of the home crowd, who may not be so eager for boss Arsene Wenger to splash the cash on deadline day.