Defender Cory Gibbs underwent surgery to repair a torn meniscus in his right knee Tuesday after sustaining the injury in training on Wednesday.
His recovery is expect to last four to six months, most likely causing him to miss the remainder of the 2012 season.
Gibbs, who has played every minute in all three Fire games this season, was an integral part of the Fire defense and a go-to guy in set pieces.
He suffered a knee injury that kept him out of the 2006 World Cup and told the Sun-Times this preseason's training camp that it was one of the more discouraging times in his career. Gibbs' latest injury is certain to similarly challenge him.
"The first couple days after hearing about the injury was basically another low point in my life," said Gibbs via a team statement. "With all the support from my wife, family, teammates and with prayer, I definitely have a more positive outlook today. I've dealt with injuries in the past and have come back to perform at a high level. I hate missing training and contributing in games so from the first day after the operation, I'm going to do everything I can to get back as soon as possible."