Manchester City surpassed 100 Premier League goals for the season and left West Ham waiting to confirm top flight football next season with a 4-1 win at the London Stadium.
After a tight opening few minutes, champions City fashioned the first chance when Sane began a move that ended when Kyle Walker crossed low but Sane, who had continued his run, failed to make a clean contact.
But after 12 minutes City were ahead when Sane picked up possession on the right and his angled strike took a big deflection off Patrice Evra and flew past Hammers keeper Adrian.
West Ham hit back well and Manuel Lanzini's dangerous cross from the right after a pass from Marko Arnatutovic was diverted away from Aaron Cresswell by Ederson.
That sparked the home fans into life, and their team created another moment of danger when a free kick was whipped in from the left before City scrambled clear.
With 20 minutes played the visitors threatened to add a second, Ilkay Gundogan teeing up Raheem Sterling who miscued his 15-yard strike.
The pace was sedate but, after 27 minutes, City made it 100 Premier League goals for the season and doubled their lead amid chaos in the West Ham defence.
Sterling was played into room on the right and, as Adrian raced out, curled a strike beyond him that was headed away before City won the ball back and De Bruyne crossed, the ball cannoning in off Declan Rice for an own goal.
David Moyes' side appeared to have suffered another setback soon afterwards as Cheikhou Kouyate went down after a clash of heads with Aymeric Laporte but, after a short delay, he was able to continue.
Sane could have made it three but Adrian did enough to put him off and the corner came to nothing.
West Ham thought they had found a route back into the match late in the first half but, in pressurising Ederson and then rolling the ball home, Arnautovic was adjudged to have fouled the goalkeeper.
They had another chance five minutes before the break when Edmilson Fernandes was fouled on the edge of the area -- and this time they made it count as Cressell stepped up to bend a strike beyond Ederson and into the corner.
De Bruyne whistled a long-range shot over the top as City looked to restore their two-goal advantage, but Pep Guardiola's men needed less than three minutes of the second half to do just that.
Their third goal came when Gabriel Jesus found Sterling, took the return pass, beat Pablo Zabaleta and slotted home from close range.
Minutes later Sterling appeared to bring down Sterling inside the area only for appeals to be waved away, and then Sterling laid the ball back fror De Bruyne to blast over with West Ham rocking.
Sterling should have made it four when he was put through by Jesus only for Adrian to block, but another goal arrived when, after 64 minutes, Sterling squared to Fernandinho who, unmarked, swept home.
West Ham made a triple change, with Javier Hernandez, Arthur Masuaku and Joao Mario replacing Lanzini, Evra and Fernandez, with City making one of their own soon afterwards as Yaya Toure came on for Gundogan.
Zabaleta hacked the ball away from almost on his goalline as City looked to add a fifth, the visitors bringing on England youth striker Lucas Nmecha for his Premier League debut, Gabriel Jesus making way.