Top 5 Countdown for Week Ending June 7

We’re featuring the five most popular songs in the Billboard Hot 100 pop singles chart, for the week ending June 7, 2014.

Something happens this week on the Hot 100…that hasn’t occurred in half a century.

Ray McDonald's Top 5 Countdown for Week Ending June 7

That’s still to come -- but first let’s swing by fifth place for DJ Snake and Lil Jon, holding steady with “Turn Down For What.”

DJ Snake says he initially wanted to sample Redman for this track. When Redman wouldn’t clear the sample, Lil Jon entered the picture…and voila! It became a big hit.

Staying put in fourth place is Pharrell Williams with with his former title-holder “Happy.” Pharrell has a busy festival season in store. This North American summer, Pharrell will log plenty of air miles. June and July find him at several European festivals, with a proper European tour kicking off in early September.

FILE - John Legend arrives at Pan African Film and Arts Festival premiere.

John Legend loses his singles crown in third place with “All Of Me,” in the wake of this week’s historic chart shift. The news isn’t all bad for John, though: this week "All of Me" takes the Billboard Adult Contemporary title. Also, John’s Love In The Future album has surpassed half a million copies in U.S. sales.

Recording artist Ariana Grande attends the Born Free Mother's Day Carnival, May 11, 2014, in New York.

Now we come to the good part: there’s a major development atop the hit list. Ariana Grande and Iggy Azalea touch it off with “Problem,” jumping a slot to second place.

Ariana is a 20-year-old singer-actress, while Iggy is a 23-year-old rapper from Australia. As a teenager, she came to the United States with the intention of becoming a star…and it seems as though her dream is coming true.

Iggy Azalea performs on stage at 102.7 KIIS FM's Wango Tango at the StubHub Center on May 10, 2014, in Carson, Calif.

Iggy and Charli XCX ascend the singles throne with “Fancy,” and that’s just the beginning: hold on for details.

Iggy Azalea jumps a slot to number one with “Fancy,” featuring British singer Charli XCX. Iggy becomes the first artist since The Beatles in 1964 to reach the top two chart positions with her first two Hot 100 singles.

Iggy is also only the third woman to concurrently hold first and second place: Ashanti did it in 2002, with Mariah Carey following in 2005.

That’s all for now, but the action never stops on the Hot 100! Drop by next week and we’ll do it again.