Goals from Islam Slimani and Jamie Vardy gave Leicester a sixth straight victory as they beat relegation-threatened Sunderland 2-0 on Tuesday.
Slimani's header from fellow substitute Marc Albrighton's cross put the champions ahead on 69 minutes, just moments after both had been introduced in the second half.
Sub Albrighton repeated the act with 12 minutes remaining, setting up Vardy for a trademark finish inside the area just moments after Victor Anichebe had hit the post with a deflected effort.
The result means bottom side Sunderland are eight points off 17th-place Swansea, while Leicester are now 10th as Craig Shakespeare preserved his 100 per cent record since taking over from Claudio Ranieri.
Leicester were unchanged after the 2-0 win over Stoke at the weekend, while Lee Cattermole, Seb Larsson and Didier Ndong started for Sunderland.
In a first half lacking in real opportunities, Jordan Pickford was called upon twice in the Sunderland goal, first tipping over Robert Huth's header at the far post.
Then, with the half drawing to a close, Pickford pulled off a superb fingertip save from Demarai Gray's long-range effort, which was heading for the corner of the goal.
The second half started off much like the first, without many chances for either side, before substitute Slimani put Leicester deservedly ahead on 69 minutes.
The striker, introduced just seven minutes before alongside Albrighton, was superbly found by the winger eight yards out, and he glanced a header past Pickford for the opener.
Sunderland nearly levelled moments later, but Anichebe's deflected effort came off the left post, before Jermain Defoe hit the side-netting from an angle.
The visitors were made to pay on 78 minutes, as Albrighton fed Vardy to finish superbly into the top left corner with his left foot from 14 yards, his seventh goal in nine games for club and country.
That's how it stayed, and the result means Sunderland have not scored in six Premier League games.
Player ratings
Leicester: Schmeichel (6), Simpson (6), Benalouane (6), Huth (7), Fuchs (6), Ndidi (6), Drinkwater (6), Gray (7), Mahrez (6), Okazaki (6), Vardy (7)
Subs: Albrighton (7), Slimani (7), King (NA)
Sunderland: Pickford (7), Jones (5), Denayer (5), Kone (6), Oviedo (6), Cattermole (5), Larsson (5), Rodwell (5), Ndong (6), Borini (5), Defoe (5).
Subs: Khazri (5), Gibson (NA), Anichebe (5)
Man of the match: Marc Albrighton
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