Former UFC Lightweight & Welterweight Champion BJ Penn, retired since a loss to Nick Diaz at UFC 137 has come out of retirement to answer the challenge of Rory MacDonald. MacDonald is coming off of a UFC 145 victory over Che Mills and made to challenge to Penn via Twitter. Penn has lost three of his last four in UFC competition, along with a majority draw with Jon Fitch at UFC 127. The battle is expected to take place at UFC 152, which will be taking place this September in Toronto, Ontario, Canada.