Baltimore Ravens defensive end Arthur Jones will miss the season opener because of an undisclosed illness and will visit a specialist on Wednesday to have tests performed.
Jones had 4.5 sacks while starting six games last year and was expected to be a starter this season.
Ravens head coach John Harbaugh did not provide specifics on Jones' illness and did not know when Jones might return.
"I'd rather leave an explanation of Art's situation up to Art," Harbaugh said Tuesday, according to The Baltimore Sun. "It's not anything that's like life-threatening or anything like that. It's non-football related. We've got to get some tests done to make sure that he's OK. Until the tests come out the right way, he's not going to be able to play.
"It's something I've been told now that they can't tell you how long it's going to be. It could be a week, it could be indefinitely. We don't think it's going to be the second part. He's going to see a specialist here on Wednesday and he can explain to you exactly what it's about, to whatever extent he wants to."
Jones did not offer details in a Twitter message, which read:
"As many of you know i'm having personal health issues. Please respect my privacy. We as athlete's go through real life problems also.Thank.."