NEW ORLEANS – While his injury appears to be the most significant, quarterback Matt Cassel wasn't the only Vikings starter to get knocked out of Sunday's 20-9 loss to the New Orleans Saints.

Cassel broke several bones in his left foot while scrambling out of the pocket in the second quarter. Cassel is out indefinitely and his broken foot could threaten to sideline him for the rest of the season.

"We will have to wait and see what it is and if he needs to have surgery," coach Mike Zimmer said.

The Vikings are also concerned about starting tight end Kyle Rudolph, who will undergo more tests on his injured groin Monday, and right guard Brandon Fusco, who hurt a shoulder in the second half.

Outside linebacker Chad Greenway started despite a broken left hand, but it was an existing rib injury that was listed on the injury report all week that shut him down late in Sunday's loss.

"I just didn't want to take away from the game [by playing when injured]," Greenway said. "That was pretty much it."

Cornerback Josh Robinson, a key reserve, also left because of a hamstring injury. He dealt with hamstring injuries during training camp and the preseason, though it's unclear if he re-aggravated an injury.

Missing Peterson

The Vikings again struggled to run the ball without starting running back Adrian Peterson, who is away from the team as he deals with his legal issues in Texas.

"It's disappointing, obviously, that we don't have him," fullback Jerome Felton said. "I mean, he's the best player in the world."

Matt Asiata got the start but rushed for only 35 yards on 12 carries. Rookie Jerick McKinnon had two carries for minus-1 yards. The Vikings as a team had 59 yards on 22 carries, and rookie quarterback Teddy Bridgewater's scrambles accounted for a chunk of that.

"We need to work on a lot of things and get better," Asiata said. "We can't look at [Peterson's] situation and make excuses. We lost the game."

More helmet issues

Zimmer said that the Vikings experienced issues with the communication devices in the helmets of both Bridgewater and Greenway, limiting their ability to make changes at the line of scrimmage Sunday.

"Those dang headsets, I don't know," Zimmer said. "That was not the first time. Out of three weeks, we've had two issues. So we need to get that fixed."

Zimmer didn't throw out any conspiracy theories about the headset issues, but consider him skeptical.

"I don't think it's the headsets, per se," he said. "This is twice in visiting stadiums that this has happened."

Third down no charm

The Vikings, who haven't been in the end zone in more than seven quarters, were 0-for-2 in the red zone and have not scored a touchdown from inside the 20-yard line since Peterson was deactivated.

"That's the part that's most disappointing," wide receiver Greg Jennings said. "It wasn't anything special that they did. … We just didn't take advantage of our opportunities and we've got to get better doing that."

Graham contained

Keeping Saints tight end Jimmy Graham, who entered Sunday's game with 18 catches for 200 yards and two touchdowns in two games, in check was one of the focal points of Zimmer's pregame preparations.

Graham was held by six catches for 54 yards with no touchdowns Sunday, but Zimmer, who isn't the type to keep track of moral victories, didn't seem all that pleased with the results.

"How many catches did he have?" Zimmer said. "We didn't cover him well enough."

Etc.

•Rookie outside linebacker Anthony Barr recorded his first career sack in the second quarter, toppling Saints quarterback Drew Brees for a 5-yard loss.

• The Vikings allowed the Saints to convert nine of their 13 third-down opportunities, including on third-and-10 and third-and-11 on their game-ending drive.

• For a second consecutive game, the Vikings did not force a turnover.