No English team had suffered such a huge loss in the 61-year annals of Europe's premier club competition and it was the worst reverse for any Premier League club in continental combat since Everton's 5-0 defeat, also in Portugal, at Benfica in the 2009-10 Europa League.
The dismal performance prompted manager Claudio Ranieri, who has overseen a poor defence of the Foxes' league title while thriving on European nights, to admit afterwards: "I want us to show our character and our strength. We didn't do that well enough.
"I have a clearer idea about my players now."
Leicester had conceded only one goal in their previously unbeaten first Champions League campaign but young stand-in goalkeeper Ben Hamer became the first English goalkeeper to concede five goals on his Champions League debut.
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He shipped three in 45 minutes with Silva starting the rout by heading home unchallenged from Corona's corner after six minutes.
One-way traffic and two brilliant goals ensued, Corona's magnificent first-time volley from Alex Telles's cross in the 25th minute being followed by Brahimi's cheeky backheel finish from a Maxi Pereira delivery just before halftime.
After a fairytale start to their European adventures which matched their Premier League heroics last season, Leicester, who had left players such as Riyad Mahrez and Jamie Vardy at home, were suddenly left with nothing but thoughts of damage limitation.
They improved markedly but Danny Drinkwater's 65th-minute foul on Silva allowed the striker to get up and slot home his fifth European goal of the season from the spot before Jota crashed home a fifth.
The best news for the hopelessly outclassed visitors was that an injury which forced Drinkwater, one of the few first-team regulars on duty, to limp off was said by Ranieri to be not serious.
With Copenhagen winning at Club Bruges in the other group game, Porto finished two points ahead of the Danish side and two adrift of Leicester.
(Reporting by Ian Chadband, editing by Ed Osmond and Clare Fallon)
