At the Emirates Stadium there was cause for concern for England boss Roy Hodgson, ahead of the World Cup qualifiers against Moldova and Ukraine, as midfielder Jack Wilshere hobbled off before half-time.
But that worry was largely forgotten by the full-time whistle as home boss Arsene Wenger, yet to make a star signing in the transfer window, expressed his delight on the touchline.
Spurs may have been without Real Madrid-bound Gareth Bale, but their £100million-plus spending spree saw plenty of talent in Andre Villas-Boas' match-day squad, with £26million man Erik Lamela starting on the bench following his transfer from Roma that was finalised on Friday.
Arsenal, having so far brought in only two free transfers, earned the bragging rights after Giroud tucked home his fourth goal in five appearances to settle an entertaining, but also heated, contest.
There was a bright start by the hosts, and Santi Cazorla forced a fine early save from Hugo Lloris with a 20-yard curling free-kick.
The Spaniard then had another go from a more central position after Theo Walcott was upended by Mousa Dembele, and this time his low effort went under the wall, bobbling just wide.
Spurs settled and Roberto Soldado, the £26million striker signed from Valencia, had a close-range shot blocked by Per Mertesacker.
Arsenal, though, swept into the lead after 23 minutes, with a swift counter from Aaron Ramsey and Tomas Rosicky seeing the ball played out to Theo Walcott down the right.
The England forward cut a pass towards the six-yard box - where Giroud arrived ahead of Spurs captain Michael Dawson at the near post to convert a lovely left-footed finish.