The second-year defensive lineman hurt his biceps on Thursday. He could miss three months because of the injury.
The Ravens will decide at the start of the regular season whether to place Urban on season-ending injured reserve or give him the designation to return.
The 2014 fourth-round pick missed his rookie season after suffering a torn anterior cruciate ligament in his right knee early in training camp. Urban was competing with veterans Chris Canty and Lawrence Guy for playing time at defensive end.
''I was really counting on him,'' Harbaugh said. ''I thought he would really shine, and I still think he will. He's had four straight years where he's had serious injuries. That's been a bugaboo for him that he's going to have to overcome.''
Urban is the second Ravens player to tear his biceps during camp, joining third-year safety Matt Elam.
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