Ainsley Maitland-Niles was sent off as we suffered another blow to our hopes of a top-four finish.
Our right back received a yellow card early in the first half and was dismissed after a second bookable offence before half-time.
It had been tough enough with 11 men - James Maddison and Youri Tielemans pulling the strings for Leicester - and Bernd Leno kept us in contention with a series of top-class saves.
Our goalkeeper denied Maddison, Jamie Vardy and Wilfried Ndidi, but he was finally beaten when Maddison’s perfect cross was headed in by Tielemans.
We had a few glimpses of goal, Alex Lacazette and Alex Iwobi spurning our best chances before Maitland-Niles was sent off.
Our work ethic could not be faulted, but we couldn’t find a way to unlock the Leicester defence with 10 men - and a late double from Vardy sealed our fate.
HOW IT HAPPENED
Unai Emery made three changes from the side that lost at Wolves in midweek.
Mesut Ozil (foot) and Nacho Monreal (calf) were ruled out with injuries so back came Shkodran Mustafi and Sead Kolasinac.
Pierre-Emerick Aubameyang also returned after a successful procedure on a sinus infection, and he lined up alongside Alex Lacazette in a 4-4-2 formation.
Our best route to the Champions League may be via the Europa League, and Valencia are in London on Thursday for the first leg of our semi-final.
Our next Premier League game is our final home match of the season - against Brighton next Sunday.
Copyright 2022 The Arsenal Football Club plc. Permission to use quotations from this article is granted subject to appropriate credit being given to www.arsenal.com as the source.