The Detroit Lions squared off against the Indianapolis Colts on Saturday as former Illinois Fighting Illini quarterback Luke Altmyer continued his pursuit of the backup quarterback job.

Altmyer and Joshua Dobbs rotated at the quarterback position with both playing a significant amount of snaps. Altmyer got the start while Dobbs played the second and fourth quarters. 

Altmyer made a pair of crucial mistakes including one that Campbell said was not his fault in a 25-16 Lions preseason victory. 

Dobbs outshined the former Fighting Illini quarterback in a winning effort as he completed 15-of-19 passes for 128 yards and two touchdowns.

The former 2017 NFL Draft choice looked crisp all day, perhaps sensing it was time to take control of the competition with Altmyer, the undrafted rookie. 

Dobbs was not sacked on the day but ran five times for -1 yard. 

Still, he protected the football much better than Altmyer, who had costly turnovers that cast doubt on his readiness to lead coach Dan Campbell's team going forward.

While Campbell has been complimentary of Altmyer in recent weeks, Saturday's performance could be seen as a major setback for the undrafted rookie NFL hopeful. 

Altmyer was also sharp passing the ball for much of the day but made two costly mistakes that social media users took note of afterward. 

He attempted to rifle a pass into a tight window during the first quarter and was intercepted by Colts star Sauce Gardner.

Upon further review, it looked like a risky pass for the former Fighting Illini star. 

Campbell said the pick was the result of a busted play. 

"The first one was not his fault," Campbell said. 

"We had a bust outside and if we did that right, that guy wouldn't have even been there. I don't blame that on Luke. There was just a couple of times where he held it too long and we've talked about that.

"I'm not discouraged by it." 

Altmyer had success throwing on the run during the first two weeks of the preseason, but Week 3 led to a costly mistake as the two-time Pro Bowler Gardner capitalized.

Another costly mistake happened with the Lions up six points in the third quarter. 

Altmyer was sacked and lost a fumble, giving Detroit's AFC East opponents a chance to seize the lead back at Lucas Oil Stadium in Indianapolis, Ind. 

Campbell was complimentary of Dobbs after the game, who appears to have the inside track to the backup quarterback position.

Altmyer showed plenty of poise and potential, but it seems likely that Campbell will choose the veteran to back up his star QB Goff after Saturday's performance.

"I thought Dobbs really played well today," Campbell said, not revealing his choice for the No. 2 quarterback spot just yet.

"I thought he really showed out and I just love his composure and conviction. 

"He knows what he wants and we scored." 

The Lions have time to prepare for Week 1's clash with the New Orleans Saints in downtown Detroit. 

Based on Campbell's comments, it's reasonable to expect Altmyer to make the Lions' roster, and to become a contributing member of the Lions' QB room moving forward.