Collison (right) celebrates his winner with Carlton Cole
West Ham moved up to seventh in the Premier League with a thoroughly deserved victory over Manchester City.
The Hammers were by far the better team throughout and Jack Collison won it in the second half, side-footing home after Shay Given saved from Savio.
Robinho had missed a sitter for the visitors, prodding wide from six yards, while he also forced a brilliant save from Rob Green with an impromptu flick.
West Ham also saw Valon Behrami carried off with a serious-looking injury.
But boss Gianfranco Zola will be delighted with the manner of their victory after outplaying City for most of the game and it provides a timely boost to their chances of qualifying for Europe next season.
The visitors, who beat FC Copenhagen of Denmark to reach the last 16 of the Uefa Cup on Thursday, appeared subdued, their play lacking any real urgency.
Craig Bellamy was their only threat, and the Welsh striker ignored the home fans' boos after his acrimonious exit from Upton Park last month to set up a glorious chance for Robinho which the Brazilian somehow poked wide.
Zola praises 'veteran' Collison
But most of the play belonged to West Ham, with Scott Parker pushing the hosts forward from midfield and Collison and Behrami and then Savio getting into advanced positions down the flanks.
Their football at times was a joy to behold but they were frequently in danger of over-playing it, always looking for that one extra pass instead of finding a killer finish.
After one such interchange Herita Ilunga found Collison but Given was equal to the 20-year-old's low shot, before another flowing move led to David di Michele shooting tamely straight at Given.
Indeed the two best chances of the first half fell to the lacklustre Robinho, who apart from missing from close-range also flicked a Vincent Kompany shot towards the bottom corner, only for Green to make a fine low save.
Just as the game was livening up, the injury to Behrami cast an enormous shadow over proceedings at the Boleyn Ground.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.