Vardy scored again on the other side of halftime after 56 minutes to put Leicester ahead once more.
Even after Danny Welbeck levelled on the stroke of halftime, Vardy restored Leicester's lead after the break.
Giroud then sent the previously despondent Arsenal fans wild when he headed the 85th minute victor from a corner, Leicester keeper Kasper Schmeichel only managing to turn the ball onto the underside of the bar before it bounced over the line.
"I can't tell you that at the moment", he said. At least you assume it was soft.
"But there's only one team that can win it and [Manchester] City brought [Pep] Guardiola to the club to win the Premier League and to win the Champions League, and he has to win something this year".
Lacazette wasted no time in removing that monkey from his back and throwing it against the wall in a way that might put both the WWF, and for that matter the WWE, on high alert.
After two straight opening day defeats, and a series of failures in the league, this really is no-more-excuses time for Wenger, who, amidst much objection, signed a new two-year contract.
"We saw it though for 83 minutes", Leicester manager Craig Shakespeare said, "and to concede two late set-plays in the manner we did is obviously hard to take". I know how important he is not only as a player but also in the group he has a big weight. The midfielder went off with a cruciate ligament injury against Southampton on May 9, 2015. "Giroud in his prime is at the top of his game".
Wenger has insisted several times that Sanchez will not be sold, although links with Manchester City continue.
Giroud headed in the go-ahead goal in the 85th minute to make Wenger look like a genius.
Craig Shakespeare's side boasted numerous players, and characteristics, that saw them shock the world to win the title in 2015/16. Captured by the Sky cameras in the stands at the Emirates, Sanchez looked far from impressed.
Arsenal didn't learn from their mistakes and were behind again 10 minutes into the second half. Left backs Nacho Monreal and Sead Kolasinac manned the middle of the defense, Giroud scored and the Gunners came from behind.
But he is no closer to shifting those deemed surplus to requirements as he believes many Premier League clubs are in the same position.