As the Vikings got back to work Monday, following their first loss since Oct. 1, they were beset by familiar questions about a topic they'd rather not have to revisit: the health and consistency of their offensive line.

It was a common theme throughout the 2016 season, and one the Vikings spent $88.5 million (as well as a third-round draft pick) this offseason trying to expunge from their memories. By the third quarter of Sunday's game against the Carolina Panthers, though, none of the players the Vikings added to improve the line — right tackle Mike Remmers, center Pat Elflein and left tackle Riley Reiff — was available to play. And it remains to be seen how many of those starters will be available Sunday against Cincinnati.

Coach Mike Zimmer said on Monday that Reiff's left ankle injury is "a lot better than he thought it was going to be." Zimmer said Reiff's ankle is not broken, and when asked if it was sprained, he said, "I don't know. You can call anything a sprain, so whatever you want to call it."

When asked if Reiff could play Sunday, Zimmer said, "Today is Monday. I'm not going to talk about injuries. We're not going to go there. There is no sense in starting already. I'll know more Wednesday when they practice."

Reiff's departure was only the latest blow to a line that was without Remmers for the fourth consecutive game on Sunday. Elflein was limited in practice all week because of a shoulder injury, and the Vikings deactivated him against the Panthers. Indications late last week were that Elflein might need to miss the Carolina game, but his injury isn't thought to be terribly serious.

By the end of Sunday's game, the Vikings had only one of their five starters — right guard Joe Berger — playing in his normal spot, and the team had more trouble protecting quarterback Case Keenum against the Panthers than at any point this season.

Keenum, who had been sacked just nine times this season before Sunday, was taken down six times, and might have been sacked on a couple more plays had he not been able to duck under defenders or slip away from Panthers rushers that overpursued him. He was pressured on 24 of his 55 dropbacks on Sunday, according to Pro Football Focus, and hit a total of seven times.

Since the bye week, Keenum has been pressured on 41.5 percent of his dropbacks — the fifth most in the NFL, according to PFF.

"We missed some things with our eyes that we've been picking up in the past," said Jeremiah Sirles, who started the game at left guard and finished it at right tackle. "We didn't turn things over combination [blocking]-wise — just little things. We've been doing a pretty good job all year of keeping the pocket clean for Case, and to give up six sacks [Sunday] really hurts. We know there's nowhere to point the blame but ourselves. We're just going to continue to come back to work, keep fighting and know that's not acceptable for the standard we've put forward this year."

Keenum put some of the protection issues on himself after the game Sunday, and wide receiver Adam Thielen said the Vikings — who ran just six times for 15 yards in the second half while trying to erase an 11-point deficit — can help themselves be more balanced if they're not playing from behind.

"When you have to pass it, the defense knows and they are teeing off," Thielen said. "We have to put those guys [on the offensive line] in a better position by scoring fast and early. Then, the defense will not know if we are running or passing the ball."

Remmers said Monday he hopes to return to practice this week, though its unclear when he'll return to game action after suffering a lower back injury in practice Nov. 29. If Remmers were able to play Sunday, it would allow the Vikings to put Rashod Hill at left tackle and keep Sirles ready for one of the interior line spots, in the event Elflein needed another week before he were able to return.

But on Monday, at least, there was a familiar sense of uncertainty around the Vikings line.

"Some guys got beat that don't normally get beat. We had some mental errors, we might have been late pushing out to a guy or something like that, but that's mostly what it was," Zimmer said. "When you have injuries, you're going to have backup players play in there. We're not going to make an excuse for this game or for players that come in or anything else. We'll take ownership of what we did Sunday, and we'll move forward."