"He will probably have to have surgery at some time," Haley told reporters. "The length of it, we're not sure, but there's some optimism. Each person it varies, but it's a difficult injury. This has been a fluid situation" Cassel got hurt during the Chiefs' loss to the Denver Broncos when he got sacked by Elvis Dumervil.
Without Cassel, the Chiefs would have to go with Tyler Palko as their starting quarterback.
And rookie fifth-round draft pick Ricky Stanzi would likely be the backup.
Palko, who has also played for the New Orleans Saints after playing collegiately at Pitt, has only played in four NFL games.
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Matt Cassel's season in jeopardy
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