Pop superstar and fan of Floyd Mayweather Jr. Justin Bieber sprayed champagne showers to cool down daytime revelers when he took over Rehab at the Hard Rock Hotel on Saturday as host for one of the Las Vegas Fight Weekend soirees. The pop prince arrived on the blue carpet shortly after 3 p.m. He showed off his six-pack abs, tattoos and Calvins and posed for photographs with Australian model Shanina Shaik, actor Kyle Massey, Vine superstar Andrew “King Bach” Bachelor, co-founder of Shots Sam Shahidi, and others.