On a slow late summer weekend at the box office, another Disney sports drama took the box office trophy. “Invincible,” as expected, was the only pic to even break into the teens, taking a solid $17 million for the weekend. Last week’s top film, “Snakes on a Plane,” lost significant altitude, and “Beerfest” and “How to Eat Fried Worms” both saw weak openings. “Idlewild” did decent biz on a relatively small number of plays. Indie comedy “Little Miss Sunshine” performed solidly in its first frame in wide release, coming in at No. 3 with $7.5 million.