Which song will reign supreme as the Song Of Summer 2015? We’re going through some of the top contenders of the year so far. Place your vote for your fave!

The competition continues! Right now, Britney Spears and Iggy Azalea's "Pretty Girls" is in a fierce fight for victory against Flo Rida's "I Don't Like It, I Love It (feat. Robin Thicke & Verdine White)." And, upon winning their respective battles, we have two more contenders going head-to-head this week: The other Elusive Chanteuse, Sia, with her haunting "California Dreamin'" cover and Idol alum Kelly Clarkson with her empowering Piece By Piece anthem "Invincible" which was, ironically, penned by Sia. (It also just got a video earlier today! Did you watch it yet?)

Check out the two songs once again for a refresher, then place your vote down below.

Fight for your fave!

CONTENDER ONE
The song: "California Dreamin'"
The performer: Sia
The producer(s): Unconfirmed
The video: No official video, but a small snippet of the track is in the San Andreas trailersuccessfully elevating it from blockbuster preview to actual art.
The reasoning: "California Dreamin'" may, admittedly, seem like an odd nomination for Song of Summer. It's a longing plea for those temperate California days during a particularly dreary winter. But Sia's spin on the classic '60s song (originally by The Mamas & the Papas) is so good that it's suitable for year-round listening. She takes a mournful track and turns it into an orchestral vision -- starting off with a slowed-down, haunting intro that tricks the listener into believing she's taking the ballad route with this one. And while Sia has the vocals to pull off a more subdued version of the song, her decision to come in strong with a booming drumbeat turns it on its head and kicks the listener awake. It brings even more depth to the track, and if you don't think Sia's version is at least better than the Beach Boys' legendary cover, we get it — but you're wrong.

CONTENDER TWO
The song: "Invincible"
The performer: Kelly Clarkson
The producer: Greg Kurstin
The charts: Debuted at No. 50 on Billboard Pop Digital Songs in March, currently uncharted
The video: It’s very much Miss Independent in a nutshell…err, big, glowing box.
The reasoning: The midtempo, orchestral tune is an arguably unorthodox choice for Song of Summer: It's not held captive by a drum machine, it won't pack a dance floor at last call and it doesn't bear a single mention of what's on ice behind the bar. But Clarkson has never been one for gimmicks, and with "Invincible," she's got her fans—who have come to expect substance over style—right where she wants them. The second Piece By Piece single, which was hand-delivered by Sia (whose unmistakable timbre serves as deliciously eerie background), speaks to Clarkson's enduring message: Even if you fall (and Miss Independent has got stumbling down to a science), your knee-scrapes will eventually calcify into a suit of armor. If she was stronger before, she's since become unconquerable.

Voting ends at 5 PM on June 2. Go, go, go!

And while you're at it, have you voted in the other round of our Song Of Summer semi-final poll between Britney Spears & Iggy Azalea's "Pretty Girls and Flo Rida's "I Don't Like It, I Love It"?