Leicester made it two wins from two matches in the Champions League as Islam Slimani's goal secured a 1-0 victory at home to Porto on Tuesday.
The striker, signed from Sporting Lisbon in the summer, netted his sixth goal in his last four games against Porto when he headed in Riyad Mahrez's cross in the 25th minute at the King Power Stadium.
The Foxes were made to work hard for victory on their home Champions League debut but withstood a late spell of pressure that saw Jesus Corona volley against the post.
Leicester's next opponents, Copenhagen, beat Club Brugge 4-0 in the other game in Group G and that result means the Foxes - two points clear at the top in the early standings - could take control of the group if they beat the Danish side in three weeks' time.
Claudio Ranieri named the same starting XI that beat Brugge so impressively in the opening group game, with Kasper Schmeichel in goal and Lucas Hernandez at right-back ahead of Danny Simpson.
In a scrappy first half regularly interrupted by the referee's whistle, Porto's best chance came inside the opening five minutes as Schmeichel came a long way out to close down Adrien Silva, who lobbed the ball goalwards and just wide of the post.
Leicester's main threat came from high balls into the box, with a long throw-in causing problems for Porto and Slimani then flicking on a free-kick into the hands of Iker Casillas.
It was Slimani who gave the hosts the lead in the 25th minute when he got in front of his marker and turned in Mahrez's right-wing cross from close range.
Miguel Layun curled a free-kick narrowly wide at the other end as Porto struggled to make an impact in open play in the first half.
Leicester, meanwhile, looked dangerous on the break and Mahrez saw a low shot saved by Casillas in the 59th minute.
That, though, was a rare opening for the Foxes in the second half as Porto upped the ante.
The visitors piled on the pressure in the final 20 minutes, with Schmeichel tipping a half volley from Hector Herrera around the post and Silva failing to control in a promising position.
Corona went closest for Porto when his deflected volley struck the post, but Leicester held out to secure a second straight win and second straight clean sheet in the group.