The new countdown is the first to feature YouTube streaming data as part of the hit list's methodology and therefore it's fitting that the New York-based Internet sensation has scored the new number one.
Baauer, real name Harry Rodrigues, becomes only the 21st artist to debut at the top since 1958, when the current chart format was launched - but he is the first essentially unknown act to crash in at number one.
Harlem Shake ends rap duo Macklemore & Ryan Lewis' four-week reign at the top of the chart with Thrift Shop, which drops to two, just ahead of surging birthday girl Rihanna, who jumps up the countdown from 57 to three with her ballad Stay.
It's a good week for the R&B star - she celebrated her 25th birthday in Hawaii with boyfriend Chris Brown and pals on Wednesday.
Stay is Rihanna's 24th top 10 on the chart, placing her ahead of Whitney Houston and the Rolling Stones on the all-time top 10 list. She's now ninth on that countdown - one hit behind Elvis Presley and three behind Sir Elton John, Mariah Carey and Janet Jackson.
Will.i.am and Britney Spears' Scream & Shout and Taylor Swift's I Knew You Were Trouble round out the new top five.
Crank up the bass - it's almost summer By now, you've removed your winter tires, dusted off your spring jacket and glimpsed at that elusive orange orb in the sky. Remember summer? It's almost back. When warm weather makes a comeback each year, there's nothing like that first drive. That first ... Read more