Denver Broncos quarterback John Elway, recovering from a right hamstring injury, left practice Thursday because of a sore lower back.
Team spokesman Jim Saccomano said Elway is still listed as probable for Sunday's home game against Philadelphia.
"With anything like this, it's kind of day-to-day," Saccomano said. "We'll see how he is (Friday)."
"It seems to be getting better and better," Elway said Wednesday. "The week off definitely helped me. It's a lot better today."
On Sept. 13, Elway strained his right hamstring in a game against Dallas. He aggravated the injury against Oakland the following week, then felt a twinge in the hamstring during pregame warmups against Washington last week and spent the game on the sideline.
Elway, 38, was a full participant in Wednesday's practice, although he didn't do rollouts or bootlegs at full speed.
"We didn't test him, we didn't sprint him for obvious reasons," coach Mike Shanahan said. "But this is the furthest he's been along at this stage of the wek since the Oakland game.
"He practiced good and said he felt pretty good. He's doing a little work on a treadmill right now, so hopefully it just keeps on getting better. Unless there's a major setback in the next couple of days, I'd be very surprised if he's not able to go."
Asked after the morning walk-through if he intended to miss another game, Elway said, "No. I don't get paid to sit on the bench. You want to play. I was playing well before I got hurt, so I want to get back out and start playing again.
"When you don't miss many games, as I haven't, and then you miss one, it kind of puts everything back in perspective. So every once in a while it's good for the psyche to miss a game, because then you realize how much you enjoy playing it."
Veteran Bubby Brister replaced Elway in the second quarter of the Oakland game and engineered a 34-17 victory. Last week, Brister made his first start since 1995 and led the Broncos (4-0) to a 38-16 victory.
Shanahan and the Broncos medical staff have attributed Elway's pregame sensation last Sunday -- which the quarterback described as a "pop" -- to scar tissue breaking loose.
The Broncos were in good health for the game against winless Philadelphia (0-4). Offensive lineman David Diaz-Infante is the only player likely to miss the game. He's listed as questionable with a knee injury.
"It takes a little longer for offensive linemen to get their legs back in shape," Shanahan said. "David is making a lot of progress, but I don't know if he'll be ready for this weekend. I anticipate him being pretty close to full-go for Seattle (the following week)."
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