Injuries: Mack 'no slam dunk' for opener

The Indianapolis Colts might not have their presumptive starting running back ready for the regular season opener.

Colts coach Frank Reich said it's "no slam dunk" that Marlon Mack is ready for Week 1, per Zak Keefer of the Indy Star.

Mack has been dealing with a hamstring injury suffered in the team's preseason opener. The upcoming week is crucial for the 6-foot, 210-pound back, according to Reich.

Mack looked poised to lead the Colts backfield after Frank Gore went home to Miami. The speedy back flashed explosiveness during his rookie campaign but struggled to pick up yards consistently behind a porous offensive line.

If Mack is unable to go against the Cincinnati Bengals in Week 1, the Colts would likely use a committee approach. Journeyman Christine Michael has gotten much of the first-team run with Mack injured. Rookies Nyheim Hines and Jordan Wilkins should also get looks. Wilkins has been the most impressive during preseason action in limited touches -- 47 yards on 13 totes and 24 yards on three receptions.

Here are the other injuries we're tracking this Thursday:

1. Buccaneers running back Charles Sims III was placed on injured reserve following his knee injury on the opening kick off of Tampa Bay's preseason game against the Titans.

2. Cardinals rookie quarterback Josh Rosen returned to practice after sitting out Wednesday's session with a sore thumb. Multiple reporters on the scene, however, relayed that Rosen was not spotted throwing during the open portion of practice.

3. Dallas Cowboys guard Zack Martin, who suffered a bruised left knee last week against the Cincinnati Bengals, said there is "no doubt" he will play Week 1 against the Carolina Panthers.

4. San Francisco 49ers coach Kyle Shanahan said he hopes cornerback Richard Sherman (hamstring) can play about a half against the Indianapolis Colts on Saturday.

5. Cleveland Browns rookie cornerback Denzel Ward suffered a back injury in the first quarter of Thursday's preseason win over the Philadelphia Eagles. In addition, Browns quarterback Tyrod Taylor left the game briefly in the first half after suffering an injury to his non-throwing (left) hand. Browns coach Hue Jackson said X-rays taken on Taylor's hand were negative. Jackson didn't provide an update on Ward after the game.

Jackson said safety Damarious Randall didn't play Thursday after experiencing tightness in his knee during pregame warmups. Linebacker Genard Avery left the game early with a hamstring injury.