Marcus Stroud will miss Week 11 due to a mystery injury.

THE ASSOCIATED PRESS

Buffalo Bills defensive tackle Marcus Stroud has been ruled out and linebacker Keith Ellison was placed on injured reserve Friday, leaving the NFL's worst run defence further depleted against Jacksonville this weekend.

The decision to end Ellison's season came after interim head coach Perry Fewell had not mentioned the move was imminent when he issued the team's injury report following practice.

Ellison has been out since hurting his quadriceps in a 31-10 loss to Houston on Nov. 1. He becomes the 12th Bills player -- and second starting linebacker, joining Kawika Mitchell (knee) -- to be placed on IR this season.

The rash of injuries continue to mount for a team coming off a tumultuous week that included Fewell taking over Tuesday for dismissed coach Dick Jauron.

Stroud was ruled out because of a knee injury that has prevented him from practising after he was hurt in a 41-17 loss at Tennessee last weekend. Except to refer to Stroud as day to day, Fewell wouldn't divulge the nature of the injury.

His absence means the Bills (3-6) could be down both starting defensive tackles against the Jaguars. Kyle Williams has missed three games because of a knee injury, and was questionable after he practised sparingly this week.

That leaves Buffalo with only two other defensive tackles on its roster, reserves Spencer Johnson and John McCargo.

The Bills are allowing an NFL-worst 173 yards rushing this season. Buffalo prepares to face the run-happy Jaguars led by Maurice Jones-Drew, who's tied for fourth in the league with 860 yards rushing and has scored seven of his 12 touchdowns in the past four games.

While strong safety Donte Whitner is set to return after missing three games with an ankle injury, the defence could be down another regular with rookie safety Jairus Byrd questionable because of a nagging groin injury. A second-round draft pick out of Oregon, Byrd has a league-leading eight interceptions to tie the Bills' rookie single-season record. He also has a five-game interception streak.

Reserve cornerback Ashton Youboty was also ruled out after hurting his ankle last weekend.

Mitchell made an appearance in the locker-room Friday. Placed on injured reserve after hurting his right knee in a 6-3 loss to Cleveland on Oct. 11, Mitchell said he had surgery five weeks ago and should be ready to begin working out in March.

The Bills filled Ellison's spot on the roster by promoting rookie defensive back Cary Harris from their practice squad.