For the second time in six years, a leg injury caused by a kick forced former middleweight champion Anderson Silva to bow out of a UFC fight. 

Silva (34-10, 1 NC), who suffered a gruesome broken leg during a 2013 title loss to Chris Weidman, was unable to continue late in Round 1 of Saturday's UFC 237 co-main event bout after an inside leg kick from Jared Cannonier (12-4) caused a right knee injury. 

The first-round TKO loss was the second straight defeat for Silva, the 44-year-old Brazilian legend who was fighting in front of a partisan home crowd in Rio de Janeiro. Although the native of Sao Paulo was reportedly negotiating a new contract with UFC entering this fight, the loss could be a particularly damaging one in relation to his future should the injury be serious. 

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Silva, who fell to 1-6 with 1 NC since 2013 during a span in which he twice failed drug tests, was able to stand and walk with help inside the Octagon after the loss but was visibly in pain. 

"I'm sorry guys," Silva said to the crowd. "In training, my knee was already really bad. I took a kick to it and my knee couldn't hold up. I'm really sorry."

The crowd instantly jeered the finish and Cannonier, 35, was barely able to conduct his post-fight interview while being serenaded with huge boos. 

"Thank you to Anderson Silva. I really appreciate the opportunity to step in here. He didn't have to fight me. He could have fought anyone he wanted to but he chose to step inside and fight me," Cannonier said. "The crowd is a different story. They don't respect me and I don't have respect for them and that's just it."

Cannonier did well to pressure Silva in the opening round with short right hands to consistently back him up to the cage. Although Silva was able to feint enough to create space, he was never able to land anything of significance.

Even after Silva trapped Cannonier in his patented muay Thai clinch late in the round, Cannonier powered out with heavy hooks that landed upstairs. Shortly after, he uncorked an inside kick which caused Silva's right knee to buckle to the side and drop him. 

Cannonier leaped in to land punches as referee Herb Dean dove in to end the fight at 4:47. 

For complete results from UFC 237, click here.