Following Usher's halftime show, Bieber posted to Instagram on Monday and congratulated the R&B superstar, 45, with whom he's collaborated on 2009's "First Dance" and 2010's "Somebody to Love ...

Despite sitting this one out, Bieber and Usher share a long-standing friendship and a rich musical history, dating back to Bieber’s early career. Their collaboration on Somebody to Love remains ...