Allen Park — Is a dress rehearsal really a dress rehearsal if the show's stars don't participate? That's the question as the Detroit Lions head into the team's third preseason game, Friday night at Ford Field against the Buffalo Bills.

It's unclear, and likely will remain so until shortly before kickoff, whether many of Detroit's key starters, including quarterback Matthew Stafford, will play in the contest. It used to be starters played the first half of the third preseason game, but philosophies are shifting around the league with the increasing frequency of joint practices replacing the need for preseason reps.

Working with the idea that the starters won't see much action, here are the players we'll be keeping a closer eye on during the game.

Quarterback

David Fales: At no point during training camp did we feel Fales had a realistic shot at Detroit's backup quarterback job, but at the very least he forced himself into the conversation with an outstanding performance in the second half of last week's game in Houston.

Fales got a late start with the Lions, signing in mid-June, and the acclimation to the scheme has been plodding. But against the Texans, things clicked, particularly with his downfield accuracy.

We don't want to overstate the value of one game — or, more accurately, one half — working against second- and third-string defenders, but with Tom Savage banged up, and Josh Johnson getting an even later start in the scheme, Fales should have an opportunity to build on his momentum.

Running back

Zach Zenner: Kerryon Johnson probably won't play much, and the team also has been cautious with C.J. Anderson, the free-agent addition signed to serve as the primary backfield complement. That opens the door for Zenner to get plenty of work and state his case for a bigger workload once the games count.

Though two exhibition contests, he's carried the ball six times, averaging a healthy five yards per carry. He also scored a receiving touchdown, carrying out a well-executed play-action fake for the 5-yard score. All that while playing extensive, effective snaps on special teams (sans a penalty against Houston).

Wide receiver

Brandon Powell: The competition for receiving jobs four and five remains wide open with two preseason games remaining. Powell has done well to this point to put himself in position to earn one of them, catching a team-high five passes for 80 yards and four first downs.

Powell is hindered by the special teams aspect of the evaluation. He offers something as a return man, but doesn't have the inside track for that role. If he's going to earn a job, it will be a result of what he brings to the table on offense.

Tight end

T.J. Hockenson: It's been a quiet, but positive first preseason for Detroit's first-round pick. He's played just 21 total snaps in the first two games, but that's been enough to highlight his potential impact, both as a pass-catcher and a blocker. Admittedly, he did learn a lesson on the latter, violating the NFL's crack-back block policy by going low on a defensive end while coming from an outside alignment.

Where Hockenson has shined during training camp is in the red zone. He's been borderline unstoppable inside five yards. You can set up those situations on the practice field, and there's no guarantee the Lions will see any snaps that close to the goal line early in the game against the Bills. But if they do, look for Hockenson to get a shot to do his thing.

Offensive lineman

Beau Benzschawel: It's looking more and more like Detroit's starting five is set, with Joe Dahl inching ahead of Kenny Wiggins and Oday Aboushi for the opening at left guard. But there's still jobs to be won on the back end of the depth chart.

Benzschawel got off to a slow start on the practice field, noticeably struggling with some of the one-on-one pass-rush work, but he's made quick strides with his technique, having greater success in that department in recent days. And Pro Football Focus has given his pass protection a favorable grade in preseason action.

Friday's game is another chance for the undrafted rookie out of Wisconsin to show he merits a longer-term investment in his development.

Defensive lineman

Mitchell Loewen: A number of players have benefited from extra reps due to injuries ahead of them on the depth chart, but few have taken advantage of them quite as well as Loewen. The big-bodied edge rusher, who played a half-dozen different positions in college, has flashed potential to disrupt the pocket, generating three pressures, including two quarterback hits, during the preseason.

With limited special teams contributions, basically just the field-goal block unit, Loewen is currently floating on that line of one of the last few to make the roster or ending up on the practice squad.

Linebacker

Jahlani Tavai: Tavai showed marked improvement with his leverage and aggressiveness taking on blocks in his second preseason performance. He figures to be in for another decent night of work with the team expected to take a cautious approach with Jarrad Davis, as he returns from a recent injury.

Defensive back

Justin Coleman: It wasn't a great first camp with the Lions for the highly touted nickelback, but he's looked much better in his 25 snaps of game action during the preseason.

The Bills offense was nothing to write home about a year ago, but the team has managed to put up 51 points so far this preseason. New slot receiver Cole Beasley, with five catches in 22 snaps of work, should provide a tough final tuneup for Coleman.

jdrogers@detroitnews.com

Twitter: @Justin_Rogers