OWINGS MILLS, Md. (AP) It's time to find out how Joe Flacco will respond to taking a hit on his surgically repaired left knee.

Flacco will start at quarterback for the Baltimore Ravens on Saturday night against the Detroit Lions, his first game action since tearing his ACL and MCL nine months ago in a game against the St. Louis Rams.

The injury ended Flacco's run of 137 straight starts. Following surgery and intensive rehabilitation, he returned to the practice field on the first day of training camp.

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Wearing a protective brace on his knee and a red jersey that serves as a do-not-touch warning to his teammates, Flacco has fared well this summer.

But he hasn't taken a blow to the knee. How he holds up in the pocket against Detroit is far more significant than completion percentage or touchdown throws.

''I don't need to get hit, no,'' Flacco said Thursday. ''But if I do, it's not a bad thing either. Hopefully, it's the same as it's always been.''

Flacco is the franchise career leader in yards passing (28,3220, touchdown throws (162) and 300-yard games (26). He was also the Super Bowl MVP in 2012.

His value to the Ravens is immeasurable. So someone asked coach John Harbaugh if he was confident Flacco could absorb a shot to the knee on Saturday.

''If I wasn't, he wouldn't be out there,'' Harbaugh said.

But the coach acknowledged, ''Football is always risky for everybody. That's just the way it works. You have to weigh the benefits with the risk.''

That point is, the Ravens don't want to wait until the Sept. 11 regular season opener against Buffalo to get a read on the status of their most important player.

''Joe's the quarterback. He's not going to break,'' Harbaugh said. ''He's going to play and we're planning on him playing really well, just like he has in practice. But it will be his first game action in a long time. I'm sure that's going to be a factor, but I'd rather have it in this game than two weeks from now against the Bills.''

Flacco agreed.

''I really don't feel like I need to play in (preseason) games to get ready to play Game One, but I want to put myself through that whole process,'' he said. ''I just think I'll be better for it. That's the reason for the whole thing.''

Flacco said watching the Ravens' first two preseason games from the sideline was ''tough.'' He probably could have played, but what was the point?

None of the starters will participate in the exhibition finale in New Orleans on Sept. 1, so this game will serve as Flacco's only tuneup for his ninth NFL season.

''That's really what I'm looking forward to, just getting back out there in live action,'' he said. ''Being in a real huddle and just seeing everybody's eyes and how excited they are to be out there.''

It's likely no one in that huddle will be more pumped as the guy calling the plays.

''I'm looking forward to getting out there,'' Flacco said. ''I'm excited about it. It's been a while obviously. I had to go through a little bit to get here to this point where I can go back out there and play with my guys.''

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