Needing a win at the Stadium of Light to go back level on points with leaders Arsenal Leicester lost to a Sunderland side requiring victory themselves to avoid relegation.
Benjamin Mbunga-Kimpioka stunned Leicester with a goal in the first minute after being set up by Jack Diamond, who assisted the second, scored by Molyneux (pictured) in the 20th minute.
Sam Hughes gave Leicester hope with a goal on his 21st birthday but Diamond restored the Black Cats’ two-goal cushion in the second half with a fine solo effort, before Molyneux struck again.
Leicester are three points behind Arsenal with only one match to go. Arsenal can clinch the title with victory over West Ham United at London Stadium on Friday.
Third-placed Liverpool are still in title contention, lying five points behind the north Londoners with two matches to play, starting at Everton this evening.
The win lifts Sunderland a point clear of the two relegation places with a match remaining. Derby County, a point below with a match in hand, can leapfrog them by avoiding a home defeat to West Ham this evening.
Sunderland: 23 Apr v Swansea (A)
Leicester: 23 Apr v Derby (H)