Starting offensive tackle Willie Colon suffered a torn Achilles, a league source told ESPN NFL Insider Adam Schefter.
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Colon will have more tests to confirm the injury on Tuesday, but the Steelers believe Colon needs surgery and five to six months of rehab, the source said.
"It looks like it's an Achilles [injury]," Colon's agent Joe Linta said. "We want to wait to confirm it, but that's kind of our worst fears."
Colon was working out in Pittsburgh doing agility drills Monday morning when the injury took place. Colon's injury was first reported by Scout.com.
Colon's potentially season-ending injury would be another big obstacle for Pittsburgh's offense to overcome in 2010. The Steelers traded receiver Santonio Holmes to the New York Jets, and starting quarterback Ben Roethlisberger will serve a conditional six-game suspension to start the season after violating the NFL's personal conduct policy.
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