It was only the second opening day victory in seven seasons for the Gunners who are coming off a torturous campaign that saw them finish outside the Champions League places for the first time in 21 years.
A insane game sees Arsenal winning 4-3 over Leicester City.
Wenger shuffled his pack and Aaron Ramsey levelled with eight minutes remaining before fellow substitute Giroud wrapped up the points.
Giroud was the match victor for Arsenal.
But the lead did not last long and within three minutes Leicester were level, Shinji Okazaki nodding the ball into the back of the net in the fifth minute.
Arsenal got off to a quick start in this one, with Alexandre Lacazette scoring just a little over a minute into the game to give himself his first-ever Premier League goal of his career.
"Of course you can not afford to concede three goals at home".
However, the lack of organisation at the back coupled with far too many errors on display on Friday night will worry the Arsenal boss, as well as the club's world-weary fans. "He has a big weight in the squad and it was a relief for me that he chose to stay".
Arsenal appeared a step behind defensively, ceding possession nearly uncontested at moments, and Marc Albrighton would make them pay, jumping on a misplayed ball from Arsenal and sending a attractive cross to Jamie Vardy who would put it away to give Leicester City their first lead of the campaign.
"We know defensively we can do better but overall we produced a top-quality game".
The guests needed only 10 minutes to regain their lead after the restart as Vardy headed in Riyad Mahrez's cross to score his side's third goal and complete his brace. We've been courageous to the end and thank God we won the game.