Claudio Ranieri's reigning Premier League champions have been in below par form domestically but find themselves sitting pretty on top of the Group G table with six points from their opening fixtures.
Known in Portugal as 'the Dragon Slayer' for his love of scoring against Porto, the Algerian again came up with the goods, this time for his new club, when ghosting in at the back post to send countryman Riyad Mahrez's pinpoint right-flank delivery home with his head in the 25th minute.
It was a deserved lead for the Foxes who had denied Porto any true scoring chances in the opening 45 minutes.
Iker Casillas was at his best for the visitors when tipping a Mahrez drive around the post just before the hour-mark before it was Kasper Schmeichel's turn to keep Porto at bay with fine save to deny Hector Herrera in the 76th minute.
Porto were unlucky not to equalise on 84 minutes when Jesus Corona struck the woodwork and despite some late pressure, it was not to be for Nuno Espirito Santo's Dragons who have only one point from their opening two matches.
As for Leicester, they are on top of their group, two points clear of FC Copenhagen who were impressive in beating Belgian side Club Brugge 4-0 in Denmark.
The next round of Group G matches take place on October 18 with Leicester hosting Copenhagen and Porto heading to Brugge.
2016/17 UEFA Champions League - Group G