INDIANAPOLIS — After the huddle broke Saturday night and he realized he’d be the top option on the ensuing passing play from 3 yards out of the Colts’ end zone, Saints fullback Austin Johnson couldn’t stop his mind from replaying what happened the last time he had an opportunity to score.

It was at St. Louis on Aug. 8, and Johnson was starting in place of fullback Erik Lorig, who joined the Saints in free agency this offseason on a four-year deal. Lorig hurt a leg at an intrasquad scrimmage six days earlier, which gave Johnson the chance he wanted.

On the play against the Rams, Johnson caught a short pass to the right around the St. Louis 2-yard line and tried to barrel past cornerback E.J. Gaines. Yet the defender got lower and dove at the Saints fullback’s legs to bring him down at the 1.

Johnson was well aware he couldn’t be denied again Saturday if he wanted to maximize his chances of landing a gig in the event Lorig is unavailable when New Orleans opens the season Sept. 7 at Atlanta.

“I was expecting a smash-mouthed run play,” said Johnson, anticipating he’d block on that first-and-goal the Saints were facing on the opening drive at Lucas Oil Field. Then they called a play in which quarterback Drew Brees would fake a handoff to running back Mark Ingram while Johnson ran out to the right flat for a quick pass.

“When they call that ... you always get a little butterflies — a little excited — because you know you’re the first read,” Johnson said. “I knew I needed to do better than I did in St. Louis and get in there.”

The 6-foot-2, 240-pound Johnson promptly had the ball in his hands, and this time the nearest would-be tackler was farther away. Linebacker Erik Walden ran up to Johnson from behind the goal line, and the Saints fullback managed to get lower than the defender and plow through him with his left shoulder. Johnson then rolled on top of Walden and into the end zone to give New Orleans a 7-0 lead en route to a 23-17 victory, improving their preseason record to 3-0.

It isn’t hard to see how that six-second sequence is a banner moment for a guy who’s had nothing handed to him so far but nonetheless finds himself very much in the discussion for a spot on the Saints’ 53-man roster.

Johnson entered the 2012 NFL draft having spent time on both sides of the ball at linebacker and fullback at Tennessee. That gave him points for versatility. But, as is sometimes seen with prospects, he wasn’t without what at least one draft site suggested was a potential off-field red flag: a 2011 arrest on accusations of public intoxication and disorderly conduct.

Ultimately, authorities dropped the case against Johnson, who paid court costs and was internally punished by Tennessee. Johnson went undrafted, signed with Baltimore as a linebacker but didn’t make the team.

He subsequently joined the Saints in 2013 as a fullback. He held on through last year’s training camp and caught a touchdown pass late in the final preseason game at Miami. But he was cut before being put on New Orleans’ practice squad.

Johnson remained there the rest of the season while former Saint Jed Collins (now with Detroit) handled the work at fullback on the active roster.

“It was a good learning experience for me, especially getting comfortable with the offense,” Johnson said. “And obviously, since I transitioned from linebacker ... just getting a whole year of fullback under my belt, and just kind of getting back into the groove of that just helped me out a lot.”

It showed when Johnson reported to the Saints for 2014. He consistently caught passes out of the backfield beginning in offseason workouts and continuing throughout training camp.

He displayed an adequacy in lead-blocking and rotated onto special teams.

Then Lorig was injured at the scrimmage, and that same day, Johnson scored off a throw close to the goal line.

Johnson was soon working with the first string in place of Lorig, who made his bones catching passes and blocking for running backs such as LeGarrette Blount and Doug Martin in Tampa Bay from 2010 through 2013.

As odds increased that Lorig’s leg issue could keep him out of action come Week 1, the Saints decided to widen their options by signing free-agent fullback Greg Jones before their preseason debut in St. Louis.

Jones appeared in all 16 games for Houston in 2013. He also blocked for running backs Fred Taylor and Maurice Jones-Drew as that duo combined for four Pro Bowls from 2007-11. Jones has 13 touchdowns, 1,384 yards from scrimmage and 345 touches on offense in the NFL.

Jones, though, has been unable to oust Johnson from the first team. That proposition is probably harder after Saturday, leaving Johnson in as good of a position as he could hope while the Saints await resolution on Lorig’s health.

“I knew they weren’t just going to give me the starting spot,” Johnson said Saturday about his reaction to Jones’ signing. “I (have been) just trying to go out there and show them what I can do and hopefully give them enough confidence that I can play.”

In Brees’ estimation, Johnson has surely and steadily been accomplishing that.

“Austin’s stepped in and done a great job whenever called upon in whatever role,” Brees said Saturday. “He’s one of those lunch pail guys: come to work, ready to do whatever’s asked of him. And he’s done that very, very well.”