However, the Premier League is ever full of surprises and a goal from Shinji Okazaki just three minutes later, followed by a Jamie Vardy goal 15 minutes before half-time, soon turned the game on its head.
England striker Jamie Vardy, who was heavily linked with Arsenal 12 months ago, scored a brace either side of a Danny Welbeck leveller that showed Arsenal's rearguard to be equally terrible from open play and set-piece situations. But it was not to be.
The Gunners trailed 3-2 with seven minutes to go before Aaron Ramsey and Giroud swung the game back in the home side's favour at a euphoric Emirates Stadium. The 30-year-old striker has been linked with West Ham United, Everton and Marseille since the arrival of club-record signing Lacazette.
"I opened the door for him at some stage [to leave], because I know that it's important for him to play", Wenger said in his postgame news conference.
'That's unmanageable so to bring one more player in for the sake of it would be stupid, but if we find an exceptional one, we will do it'.
"But of course at the moment I have now 33 players and it is very hard to manage on a daily basis such a high number".
"Not only as a player, he is a fantastic player, but as well in the group".
"Not only as a player, he is a fantastic player, but as well in the group - he has a big weight in the squad and it was a relief for me that he chose to stay". "It's a determined no".
Leicester's wantaway midfielder Riyad Mahrez is expected to start on Friday, despite publicly expressing his desire to leave the club at the end of last season.
He stretched Nacho Monreal and Rob Holding at every opportunity, ghosting past both players to score Leicester's second from Marc Albrighton's sumptuous left wing cross after five minutes.
"We were never close", he added when asked about Arsenal moving for Mahrez.
"We're gonna win the league!" sang the Leicester fans and they nearly had a third goal to cheer when Okazaki's header from Christian Fuchs's cross bounced just wide of Cech's left-hand post.
"He came out and made a statement which we are all aware of but while he trains and plays and is professional the way he is, he will be considered for selection".