The Premier League returned to action after last weekend's games were postponed following the death of Queen Elizabeth II and there were minute's silences and renditions of the national anthem at all Saturday's matches.
In north London, South Korea star Son responded to being dropped by hitting an incredible hat-trick.
Son came off the bench to score Tottenham's last three goals, including a pair of brilliant long-range finishes, in an emphatic victory that lifted them into second place.
It was the ideal response from Son after he had been axed by boss Antonio Conte for failing to score in his previous eight appearances.
"My finishing has been poor this season. I've also been a little bit unlucky. I knew goals were coming and I wasn't worried," Son said after unbeaten Tottenham's fifth win from seven league games.
Conte added: "I am really happy for Sonny, you know what I think of the player. I said to him if you're going to score three goals maybe we can repeat this experiment!
"Sometimes to start on the bench and to come on is important because in the next game you are recharged mentally and physically."
Bottom of the table Leicester's sixth successive defeat will pile pressure on boss Brendan Rodgers after his outspoken criticism of the club's failure to back him in the transfer window.
Youri Tielemans had put Leicester ahead with a retaken sixth minute penalty, but Harry Kane headed Tottenham's equaliser two minutes later.
Eric Dier nodded the hosts in front after 21 minutes before James Maddison's half-volley drew the Foxes level in the 41st minute.
A pulsating half finished with Rodrigo Bentancur blasting Tottenham back in front from the edge of the area.
Introduced for Richarlison in the 59th minute, Son stole the spotlight as he curled a brilliant long-range strike past Danny Ward in the 73rd minute.
Son struck again with an even better finish from 20 yards in the 84th minute.
The 30-year-old completed his memorable cameo with a clinical effort two minutes later, celebrating by triumphantly raising three fingers after the goal survived a VAR check for offside.
At St James' Park, Newcastle had to settle for a point for the fifth time in seven games this season as Bournemouth earned a 1-1 draw.