Over the course of the summer so far, the Hot 100’s been defined by its lack of movement. This week’s Top 10 is almost identical to last week’s, which was almost identical to the week before–four songs remain in the same positions, and the remaining six have only moved up or down by one or two slots.

These small changes can still produce significant drama. At the very top of the chart, Australian rapper Iggy Azalea’s seemingly unbeatable “Fancy” and Canadian faux-reggae group Magic!’s virally popular “Rude” have traded places, knocking “Fancy” out of the top spot and ending its record-setting seven weeks at number one.

Even more significant is Disclosure’s “Latch” finally breaking into the Top 10 at number 10, up from number 12 last week. The Sam Smith-fronted vocal house track spent 17 weeks slowly climbing to this point. (Smith’s “Stay With Me” remains steady at number 5.) While “Fancy” and “Rude” have proven to be divisively popular, “Latch”‘s quirky but catchy 6/8 beat and Smith’s massively addictive falsetto vocal hook are the type of thing that can turn a song from a regular old hit to a consensus smash like “Get Lucky” or “Royals”—the sort of thing pop fans have been waiting to emerge as the defining song of this summer. The only problem is that while “Latch” has only been on the Hot 100 for a few months, it’s been out for nearly two years now, and to its core audience of dance music fans it’s kind of old news.

Meaghan Trainor’s “All About That Bass” entered the Hot 100 this week at a modest number 84, but it has “viral hit” written all over it in big pink bubble letters. It’s got the same kind of giddily retro aesthetic that helped drive the popularity of Amy Winehouse’s “Rehab” and CeeLo Green’s “Fuck You,” a body-positive message wrapped up in a cute metaphor, and an infinitely re-watchable video. “Bass” is an enthusiastically affable song, and out of every song on the Hot 100 it’s the one that’s the most unabashedly fun. It could very well be the summer jam that everyone’s been waiting for.