Arsene Wenger's substitutions inspired the Gunners' comeback as substitute Ramsey fired home with seven minutes to go to level the scoreline.
"Lacazette is simple - in every game he's stronger since he joined us", said Wenger, who had seen his side lose at home in three of their previous four opening league fixtures.
"Aaron Ramsey - I did not want to take a chance with him tonight because he got injured in the first game of last season against Liverpool".
You want the Premier League to be the best league in the world and I think it has to produce this kind of game to produce interest and quality.
When Alexandre Lacazette, Arsenal's new forward, netted the season's very first goal in the second minute of the game, the tone of the game looked set. Lacazette was excellent on his debut, scoring after 94 seconds before having a crucial hand in Danny Welbeck's equaliser just before half-time.
In Leicester's title winning season they lost both meetings with Arsenal, 2-5 and 2-1. There was still plenty to do, but somehow Lacazette found the pace and the direction to plant a header into the bottom corner, with not even two minutes showing up yet on the clock.
This was the ideal lift-off for Arsenal, particularly for Lacazette. Egypt global Mohamed Elneny sent a cross that was met by Lacazette, who headed the ball beyond Kasper Schmeichel.
However, it's quite well known Arsenal haven't fared to well on the opening day of the season lately. Arsenal's defence, though, was still on its summer break.
It brings him level with former Arsenal favourite Kevin Campbell, who breached Manchester City swiftly at Highbury in 1994, while Colombia great Faustino Asprilla also punished Sheffield Wednesday in the second minute of the 1997-98 campaign while at Newcastle United.
Marc Albrighton's deep cross caught out the Arsenal backline, including goalkeeper Petr Cech, and led to Harry Maguire's knock-down finding Okazaki, who made no mistake with his close-range header.
Before completing a half-hour of the season, Arsenal was trailing. "One was a corner, one on build-up, one on a corner again", he said.
How quickly optimism faded as Arsenal's enduring defensive flaws were exposed so soon.
I'm not saying he should be Arsenal's number one striker; that wouldn't be enough if Arsenal were trying to win a Premier League or Champions League which a club of this size should be.
Leicester couldn't stay on top, though.
Substitute Ramsey smashed in an angled drive - from a corner which was won after Mesut Ozil handled in the build-up - before Giroud showed athleticism and strength to meet Granit Xhaka's corner.