METAIRIE — It has been a rough week for the New Orleans Saints defense.

First it played its worst game of the season in a 48-46 home loss to the San Francisco 49ers in an NFC showdown.

It gave up 516 yards and five touchdown passes and allowed the 49ers to drive 63 yards in the final minute and kick a winning field that took away the Saints’ control of the battle for the top seed in the NFC playoffs.

Then the team placed two key defensive starters – tackle Sheldon Rankins (ankle) and end Marcus Davenport (foot) – on injured reserve this week because of injuries sustained in the loss to San Francisco.

The defensive line has been perhaps the deepest position on the Saints this season, but there will be a drop-off after losing two starters. New Orleans plays Indianapolis on Monday night in the Mercedes-Benz Supedome.

“One of the things this year that we felt was beneficial was our depth at the defensive line position, carrying eight each game and getting into a rotation,” coach Sean Payton said. “So that when you lose two starters, the depth helps you, but the next week you aren’t at eight again. We have a couple of guys that we will be training this week to get ready. Those other players are stepping in and will have to step up.”

The Saints signed five-year veteran tackle T.Y. McGill and four-year veteran end Noah Spence to replace Rankins and Davenport.

“There’s a vision with each one relative to what they do well and how we would use them,” Payton said. “They are in good football shape and I’m anxious to see how they do.”

Rankins missed the first three games of the season as he worked his way back from Achilles surgery in January. He had two sacks and 10 tackles.

Davenport, a former No. 1 draft choice, who was slowed by a toe injury as a rookie last season, had six sacks and 31 tackles. He’s second on the team in sacks behind Cameron Jordan, who leads all NFL ends with 13.5 sacks but was limited in practice Thursday because of an abdominal injury.

David Onyemata has been starting ahead of Rankins since the second game of the season, though the two essentially shared the position. 

Veteran Mario Edwards Jr. has been more of a factor recently. Edwards has had one tackle in each of the last three games, including his only sack, after having no tackles in seven straight games.

Rookie tackle Shy Tuttle has been a regular member of the rotation behind nose tackle Malcolm Brown even before Rankins was hurt. 

He said the defense’s performance against the 49ers left “a bad taste in our mouth.”

“We gave up 48 points,” Tuttle said. 

“It wasn’t our best defensive showing. We knew we had a bunch of mistakes to correct. 

“We gave up 48 points as a defense, so that should speak for itself.”

Trey Hendrickson figures to start in Davenport’s place. Hendrickson got off to a fast start this season with three sacks in the first two games before being slowed by injury himself. 

He was inactive for three straight games, but has been regaining form. He had his first sack since September against Atlanta on Thanksgiving night. Rookie Carl Granderson also figures to see more action at end.

“We expect to do our job, which is play hard and play fast,” Granderson said. “(Rankins and Davenport) mentored me a whole lot. They’ve been good roles models and I’ve learned a lot from them.

“I hate to see those guys go down, but our opponents don’t care who gets hurt. 

“We’ve got depth at every position with backups who are similar to starters.”

The Saints have been resilient with injuries to key players this season. 

Quarterback Drew Brees missed five games due to a thumb injury and New Orleans won each game.

They’re 10-3 and headed to the playoffs even though other key players such as running back Alvin Kamara, tight end Jared Cook, cornerback Marshon Lattimore, linebackers A.J. Klein and Kiko Alonso as well as offensive linemen Terron Armstead and Andrus Peat have missed time due to injury.