Hurt Josh Koscheck out of UFC 163

Former top welterweight contender Josh Koscheck suffered an undisclosed injury that has forced him out of an Aug. 3 bout with Demian Maia at UFC 163 in Rio de Janeiro, promotion officials announced Friday.

Koscheck becomes the latest high-profile competitor to fall off the card due to injury.

Top lightweight contender Anthony Pettis was slated to face featherweight titleholder Jose Aldo in the UFC 163 main event. But Pettis, who was to make his featherweight debut, suffered a knee injury while training and withdrew from the fight.

Featherweight contender Chan Sung Jung, who replaced Pettis, will attempt to lift the 145-pound belt against Aldo in the main event.

The 35-year-old Koscheck (17-7) was hoping to snap a two-fight losing skid. In his most recent outing, on Feb. 23, Koscheck was knocked out in the first round by Robbie Lawler.

In his bid to capture the welterweight title, Koscheck was beaten handily by champion Georges St-Pierre on Dec. 11, 2010, at UFC 124 in Montreal. Koscheck failed to win a single round in the unanimous decision loss.

Maia (18-4) has won three fights in a row. He is ranked fifth among 170-pound mixed martial artists by ESPN.com.