1. Get sputnik skull.
2. Continue through the level intill you get in the gauss hog, after you defeat the wraith you come out of the building, park under teh building in front of you with a giant chunk missing from it.
3. jump on the platform below the giant crack and grenade jump in to the building (this may take multiple attempts)
4. When halfway up the interior of the building turn around and you will see a big metal rod, jump on to it.
5. Once on it you can jump to another rod and get to the rooftop, from there you can push the soccer ball down.