Tickets have sold out for pop superstar Rihanna’s concert at Istanbul’s İnönü Stadium on May 31, while another global pop heavyweight Justin Bieber has just announced his own Istanbul appearance.

Rihanna, whose name has recently been in the headlines for her tumultuous relationship and controversial world publicity tour, released her seventh studio album, “Unapologetic,” on Nov. 19, 2012 through Def Jam Records. It was recorded over the course of five months during promotion of her sixth studio album, “Talk That Talk.”

Justin Bieber has been slated to grace Istanbul with his presence this spring, also at the İnonu Stadium. The tickets are selling like hot cakes, the first category having sold out within a few hours. Bieber’s third studio album “Believe,” was released on June 15, 2012 through Island Records. It marked a musical departure from the teen pop sound.