Guard Mike Iupati before the snap in the preseason opener against the Chiefs.

The Cardinals' defensive line wasn't the only group to take a significant injury hit during practice this week.

While the season-ending torn Achilles for nose tackle Corey Peters was the biggest blow, coach Bruce Arians said Pro Bowl left guard Mike Iupati could miss between three and eight weeks as he undergoes surgery to repair his meniscus.

Iupati left practice early on Tuesday, and la

st year's starter, Ted Larsen, assumed his spot with the first team.

"It's nothing serious, but each guy's a different timetable," Arians said.

The Cardinals open up against the Saints on Sept. 13, which gives Iupati an outside chance of not missing any regular season games if the recovery is quick. The longer end of the spectrum could keep Iupati on the sidelines through the first four or five games.

Larsen started all 16 games for the Cardinals at left guard in 2014. He entered camp battling for the starting job at center, but moved back to guard after the Cardinals re-signed center Lyle Sendlein.

"We still have Ted and he's stepping in doing a great job," right guard Jonathan Cooper said. "He has plenty of games under his belt, so that will be fine. And then we have depth with Earl (Watford). It's just a matter of staying together, not letting it worry us too much and continuing to play ball."

Cooper has played left guard most of his career, but moved to the right side when Iupati was signed as a free agent this offseason. Cooper said the plan is to stay at right guard. He expects the offensive line to manage this injury until Iupati can return. Arians also said Watford could battle his way into the starting job.

"You feel bad for (Iupati) but the team has to move forward," Cooper said. "And when he gets back I know he'll be ready to roll."

CHRIS JOHNSON EXPECTED TO MAKE CARDINALS DEBUT SATURDAY

Running back Chris Johnson has assimilated quickly at training camp this week and Arians would like to get him five or six carries on Saturday against the Chargers. Arians will still keep it simple for Johnson as he learns

the offense.

"I don't want to stick him in a situation where he's stuck in a blitz pickup that he's unsure of and the quarterback gets hit because he's still learning our system," Arians said. "But the things he's familiar with, we'll try to get him out there and get him some football."

Johnson had an ice pack on his right leg walking to the locker room after practice on Thursday, and it's unknown if a possible injury will affect his availability.

Arians said rookie running back David Johnson is expected to play some of the second quarter and the entire third. He missed the preseason opener with a hamstring injury.

 Linebacker Sean Weatherspoon (hamstring), linebacker Shaq Riddick (hamstring) and tackle Rob Crisp (knee) will miss the game, but Arians hopes to get them back next week. Wide receiver Michael Floyd (hand) and cornerback Jonte Green (hamstring) are still out.

INCONSISTENCY HOLDING BACK HUMPHRIES

The Cardinals could have two projected starting offensive linemen out in the early part of the season if right tackle Bobby Massie misses some action along with Iupati. At this point, it seems first-round pick D.J. Humphries will need to make strides quickly if he wants to be a viable option at tackle.

Veteran Bradley Sowell has been working with the first-team at right tackle over Humphries and indications are Sowell is next in line if needed.

"Bradley's a pro," Arians said. "He shows up every day. D.J., he shows up once every week."