The Baltimore Ravens have ruled defensive end Arthur Jones out for Thursday's season-opening matchup at Denver due to an undisclosed medical issue.
Head coach John Harbaugh declined to offer specifics on the condition of Jones, a projected starter on the defensive line for the defending Super Bowl champions, while speaking to reporters on Tuesday.
"I'd rather leave an explanation of Art's situation up to Art," Harbaugh remarked. "It's not anything that's life-threatening, or anything like that. But it's not football related. We just have to get some tests done on it to make sure he's OK. And until the tests come out the right way, then he's not going to be able to play."
The Ravens have yet to determine a timetable for Jones' return as well.
"It could be a week, it could be indefinitely," said Harbaugh. "We don't think it's going to be the second part, but he's going to see a specialist here Wednesday."
Veteran Marcus Spears will likely fill in for Jones, who recorded 47 tackles and 4 1/2 sacks while starting six of Baltimore's 16 regular-season games in 2012.