Doubt once again casts its shadow over Dricus Du Plessis.
The 31-year-old South African will defend the undisputed Ultimate Fighting Championship middleweight title when he faces the unbeaten Khamzat Chimaev in the UFC 319 headliner on Saturday at the United Center in Chicago. Du Plessis enters the cage on the strength of an 11-fight winning streak. He last suited up at UFC 312, where he took a five-round unanimous decision from Sean Strickland in their Feb. 8 rematch. Du Plessis, who has not experienced a setback in almost seven years, nevertheless steps into his latest assignment as a betting underdog.