Bruno Mars' "When I Was Your Man" advances 2-1 on the Billboard Hot 100, granting the pop singer/songwriter his fifth leading title. It also marks just the second No. 1 in the chart's more than five-decade history for a song featuring piano and vocals exclusively.
Each Friday, Billboard presents "Bubbling Under," a weekly look at new and noteworthy acts making their way toward Billboard chart success. Up this week: MKTO, Houndmouth, Kayla Brianna and Shine Bright Baby.