The match seemed to be following the normal script as the Gunners trailed the visitors 3-2, until Aaron Ramsey levelled things up with seven minutes on the clock, before Giroud sealed the three points in the 88th minute with a thunderous header.
Giroud had been seriously considering his future following the £52 million club record signing of Alexandre Lacazette and Wenger's certainty but has been persuaded to stay in what is now a "super sub" role.
The possibility of a turnaround seemed to be disappearing for Arsenal until Arsene Wenger made an ispired double switch that swung the game back in his side's favour.More news: Pioneer Library System to focus on solar eclipse
"It is fantastic", Wenger replied when asked about Giroud's willingness to fight for his place.
"No. It's a determined no", he said. Just a few minutes later, he would net the goal that would secure the win for Arsenal to start the season.
"It's impossible to keep them happy when strikers don't play".
"I feel as well that the goals we conceded we can work to get rid of that because one was a corner, one was a ball we lost in the build-up and the third goal was on a corner again so we conceded two goals from corners".More news: UN OKs new sanctions vs N. Korea. What next?
Leicester boss Craig Shakespeare was also pleased - even if the Foxes headed back to the East Midlands with nothing to show for their evening's endeavour. "To come away to the Emirates, score three goals but concede four is disappointing especially as a defender".
'Tonight we needed this win, everyone knows the importance of the first game for confidence.
'We wanted someone who would play attacking, attractive football, that is a core part of this football club, and finally someone who would give young players a chance.
Mahrez, who has been linked with a move to Arsenal in the past 12 months, had been a target for Roma.More news: Advice from an eye doctor on viewing the eclipse safely
"I don't know how good everyone will be".
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