Five things to watch in Falcons’ game

After facing a rookie and a journeyman quarterback, the revamped Falcons’ defense will face its stiffest challenge of the exhibition season against Ryan Tannehill and the Miami Dolphins at 7 p.m. Saturday at Sun Life Stadium.

In the third game, with most starters set to play into the third quarter, the defense will face Tannehill, who has a career 84 passer rating over 48 starts. The Falcons’ starting defense shined in the first two exhibition games, against Tennessee rookie Marcus Mariota and New York Jets’ quarterback Ryan Fitzpatrick, who’s with his sixth NFL team.

“We definitely have a big test in front of us,” defensive tackle Jonathan Babineaux said. “We are looking forward to the challenge. It’s going to be a big test to see where we are at as far as the defensive unit.”

The Falcons’ defense finished last in the league in yards allowed (39.8.3), yards per play (6.14), passing yards (279.9) and third-down conversions (46.8 percent) in 2014.

But the Falcons are not in awe of Tannehill and the Dolphins, who are coming off back-to-back 8-8 seasons.

“We go against a really good offense every day,” free safety Ricardo Allen said. “We go against Julio (Jones), Matt Ryan and all of them.”

Here are five things to watch Saturday:

1. Blocking Suh: The Dolphins signed defensive tackle Ndamukong Suh to a six-year, $114 million contract in the offseason to anchor their defense.

The Falcons are still trying to configure the interior of their offensive line, with competition focused at center and left guard, where Joe Hawley and James Stone have been working with the first-team.

2. Coleman's debut: Rookie running back Tevin Coleman, who's coming off a hamstring injury, is set to make his debut.

The offense has rushed 53 times for 100 yards for a paltry average of 1.9 yards per carry.

Falcons coach Dan Quinn said the team spent a lot of time trying to fix the running game in practice after the Jets’ game.

3. Pass rush: The pass rush has been outstanding against the Titans and the Jets, with Adrian Clayborn and Tyson Jackson getting sacks.

“I don’t think we are where we want to be yet,” Babineaux said. “This game is going to really dictate how we go into the season with it. I’m ready to get after Tannehill.”

4. Hageman's return: Defensive tackle Ra'Shede Hageman started the opener, but missed the Jets game while in the league's concussion protocol.

Babineaux, a starter since 2008, has made way for Hageman.

“I’m fine,” Babineaux said. “I brought into the system since Day 1. I respect what coach Quinn has done since he’s been here with his staff. I’m going along with it.”

5. Collins' improvement plan: With starting cornerback Desmond Trufant (shoulder) not playing, rookie cornerback Jalen Collins' NFL crash course will continue.

With the Falcons desperately looking for a big cornerback, he’ll get more snaps to continue his development.

He was shaky while playing 20 snaps against the Titans and 36 against the Jets.

Collins, a second-round pick from LSU, is going through the same process that Desmond Trufant and Robert Alford did two years ago under former coach Tim Lewis.

Defensive backs coach Marquand Manuel has been coaching Collins hard, trying to make up for OTA time he missed while out after foot surgery. Manuel contends that Collins has to understand what it takes to compete on every down and finish plays.

“That’s what Trufant had to go through,” Manuel said. “That’s what Robert had to go through. Jalen is going to have to go through that same process of learning how to compete down-in and down-out. Every play counts. When you get to that relentless effort, he’ll be fine. That will fix the critical errors that happened in the (Tennessee) game.”