A knee injury has forced Anthony Pettis (16-2 MMA, 3-1 UFC) out of August’s UFC 163 main event, and “The Korean Zombie” Chan Sung Jung (13-3 MMA, 3-0 UFC) has stepped in as an injury replacement and will now fight UFC featherweight champion Jose Aldo (22-1 MMA, 4-0 UFC) for the title. UFC President Dana White today announced the news. UFC 163 takes place Aug. 3 at HSBC Arena. The main card airs on pay-per-view following prelims on FX and Facebook. The extent of Pettis’ injury wasn’t disclosed. Aldo is riding a 15-fight win streak that includes eight straight WEC/UFC title defenses.