METAIRIE, La. -- Reinforcements are on the way for the New Orleans Saints' defense.

First-round draft choice Sheldon Rankins is expected to make his NFL debut Sunday at the San Francisco 49ers after the defensive tackle began the season on injured reserve with a broken fibula suffered in training camp.

"He's gettin' around good. And we anticipate this is the week for him," Saints coach Sean Payton said of the defensive tackle from Louisville, whom the Saints selected with the No. 12 pick in the draft.

Rookie defensive tackle Sheldon Rankins will give the struggling Saints defense a boost. Derick E. Hingle/USA TODAY Sports

This is the first week Rankins is eligible to play under the NFL's rule for players coming off of injured reserve. He began practicing the first day he was eligible two weeks ago.

The Saints' injury-riddled defense is also likely to get top cornerback Delvin Breaux back Sunday from his own broken fibula, which he suffered in Week 1. Breaux declared himself "115 percent" healthy on Wednesday after participating in team drills for the first time -- though he stressed that it remains a coaches' decision.

Both developments are huge for a defense that got off to an abysmal start this season before showing recent signs of growth. After an 0-3 start, the Saints are now 3-4. And after two solid defensive performances in a row, they now rank 28th in yards allowed per game (397.4) and 31st in points allowed per game (30.7). Only the 49ers are worse.

Rankins will probably be on some sort of pitch count in his NFL debut -- especially at a defensive tackle position where the Saints do a lot of rotating in general. The good news is that veteran Nick Fairley has been a strong addition for New Orleans at the same three-technique tackle position, with 3.5 sacks. The two of them might even play side-by-side in pass-rushing situations.

Rankins (6-foot-2, 305 pounds) was a versatile and disruptive presence at Louisville, with 14 sacks and 26.5 tackles for loss over his final two seasons. He showed signs of promise in the summer -- highlighted by an interception against Tom Brady during joint practices with the New England Patriots.