Manchester: Leicester stunned Manchester City 3-1 on Saturday to bolster its bid to become the unlikeliest champions in English football history.
Leicester, which was fighting relegation from the Premier League a year ago, is now six points clear of second-place City following an unexpectedly easy win at the home of the 2012 and 2014 champions.
Leicester wasn't even reliant on top-scorer Jamie Vardy. Defender Robert Huth scored inside three minutes and again on the hour after Riyad Mahrez netted at the start of the second half. Sergio Aguero claimed a late consolation.
Leicester has never won the top flight and its squad wasn't assembled by spending hundreds of millions of pounds like City. City also remains in both domestic cup competitions and the Champions League, Leicester's only focus is the league.
City had hoped to pull level with Claudio Ranieri's men at the top of the table but instead ended the day trailing them by six points.
This was City's first home game since the announcement that Pellegrini was leaving at the end of the season and being replaced by outgoing Bayern Munich coach Pep Guardiola.
Leicester's display - loaded with speed and energy - could mean Pellegrini does not leave a Premier League winner for a second time.
The warning signs were evident from early on and Leicester never allowed City's vulnerable central defensive duo of Martin Demichelis and Nicolas Otamendi to settle.
Leicester caught the hosts napping with the first opportunity after three minutes. Mahrez's free kick bounced through the area from the right and Huth was the quickest to react six yards out.
Demichelis tried to get his body in the way of the German's flicked shot but succeeded only in diverting it past the helpless defender Joe Hart.
City was ragged and things could have got considerably worse as they were pulled apart continually in the opening 20 minutes. Hart needed to be alert to smother an effort from Vardy and was then quick off his line to deny Danny Drinkwater after another quick counter-attack. Shinji Okazaki also narrowly failed to turn in a dangerous cross from Vardy.
Too often City's pressure failed to result in chances that threatened Kasper Schmeichel's goal. Yaya Toure blasted over and David Silva guided an effort wide. When Aguero did find the target, Schmeichel was in the right place.
Leicester upped the tempo and doubled the lead through Mahrez three minutes into the second half. The Algeria international picked up the attack after a break by Wes Morgan and skipped over a challenge from Otamendi. He then wrong-footed Demichelis before firing a blistering shot past Hart.
City responded, with Schmeichel keeping out a powerful header from substitute Fernando before Huth headed in Leicester's third. The former Chelsea defender rose above Demichelis and Aleksandar Kolarov to head into the top corner from a corner.
That goal killed off all hope of a City revival and Leicester remained in control. Aguero did pull one back by heading in a Bersant Celina cross three minutes from time but the game was already up for the hosts.