The Emirates Stadium exploded with joy, but they were sitting down, shaking their heads soon after as a quick corner caught Arsenal out and Shinji Okazaki, of all people, rose to head home the equaliser for the 2015-16 champions.
Just 160 seconds after Lacazette scored, Arsenal goalkeeper Petr Cech was picking the ball out of his net.
"Giroud is fantastic. I opened the door for him".
In a separate pitch-side interview he added: "I love Giroud the player".
It was an incredible escape act from Arsenal, but Giroud claimed his team, who dominated possession and peppered the Leicester goal, never doubted they would hit back.
Obviously, with this being the first game of the season, Arsenal is going to be top of the table for at least the next 12 or so hours until the rest of the Premier League plays on Saturday. But I don't want him to go and in the end he chose to stay and it was one of the days of recent weeks for me because I know how important he is.
Instead, Wenger avoided a third consecutive season-opening loss at the start of his new two-year contract.
When pressed if the forward could leave before the end of the transfer Wenger responded emphatically: "No".
"He has a big weight in this squad, and it was a relief for me that he made a decision to stay".
It was tough on Leicester and, in particular, their own striker Jamie Vardy who scored twice and was as sharp as a tack.
In the 67th minute Giroud and Ramsey were brought on for Elneny and Holding, and those men would help turn the tide in Arsenal's favor.
The Premier League's opening game saw Leicester travel to Arsenal, and for Gunners fans things started with a stirring optimism.
The Serie A side have now said they will not increase their offer and Shakespeare is happy to have Mahrez in the team.
'We have many games and hopefully I can give a good number to all the strikers.
He said: "At some stage it didn't look like we'd win".
"There were hard moments when we were down and we managed to get out of that and it's great to see".