Less than 48 hours after firing Nick Sorensen as defensive coordinator, the 49ers turned to someone familiar as a potential replacement.

The team interviewed former New York Jets coach Robert Saleh and current Lions defensive backs coach Deshea Townsend for the opening.

Based on what coach Kyle Shanahan said Wednesday, he’s just getting started. One of the reasons Sorensen was dismissed was the number of quality candidates available and Shanahan plans to take full advantage.

“I feel there are some options out there that can end up being a better option in the situation that we’re in for our team,” Shanahan said. “And when really it comes down to that, in the position I’m in, regardless of anything else, that’s always the stuff I’ve got to go with.”

Saleh coordinated the 49ers defense under Shanahan from 2017-2020 before being hired as the Jets head coach. His energetic presence brought vibrancy to the 49ers sideline and enlivened the defense, which drove the 2019 team to a Super Bowl appearance and finished top-five in fewest yards allowed each of his last two seasons.

His run with the Jets was much less successful as he never won more than seven games in a season, and the signing of quarterback Aaron Rodgers — plus his subsequent injury — turned up the already bright lights in the New York media market. He was fired in October after starting the season 2-3, and was 20-36 overall as a head coach. Former 49ers linebacker Jeff Ulbrich — another potential defensive coordinator candidate — took over for him on an interim basis and the team sputtered to a 5-12 record.

It remains to be seen whether Saleh will be available to the 49ers. The Jacksonville Jaguars announced Saleh as a candidate on “X.” He’s scheduled to interview Tuesday. According to several media outlets, Saleh is also in play as a Raiders head coaching candidate after the firing Wednesday of Antonio Pierce after one season.

Saleh signed on with the Packers in late October as a consultant. Green Bay plays at the Eagles on Sunday in the wild-card round of the playoffs.

Whoever the 49ers hire, it will be their fourth defensive coordinator in four seasons after DeMeco Ryans, Steve Wilks and Sorensen. Ryans left to become head coach of the Houston Texans after two seasons running the 49ers defense and previously serving as a quality control coach and inside linebackers coach before replacing Saleh.

Wilks and Sorensen were each fired after one season, although Sorensen is in play to remain on the 49ers staff, possibly as a special teams coach to replace Brian Schneider. Schneider was fired after three years with the 49ers.

In his role as an offensive consultant for the Packers, Saleh described his role as “fluid” under head coach Matt LaFleur, with whom he first worked in 2008 on the Houston Texans staff that included Shanahan as offensive coordinator. LaFleur was best man at Saleh’s wedding, and presumably his hire with the Packers in a consulting job wasn’t going to preclude accepting another job in the future.

Townsend is a former longtime Steelers cornerback who has managed secondaries across the NFL over the last decade. He has been a defensive backs coach for the Titans (2016-17), Giants (2018, assistant), Bears (2019-21), Jaguars (2022-23) and Lions (2024). The last two stops have included duties as the defensive passing game coordinator.

Detroit allowed the lowest passer rating (82.0) of any team in the NFL this season.

Aside from Ulbrich, who was sought by the 49ers a year ago but was blocked by the Jets, other candidates to replace Sorensen could include Lou Anarumo, who was let go as the defensive coordinator of the Cincinnati Bengals, and Patrick Graham of the Raiders, who is free to negotiate with any team.

Shanahan said Brandon Staley, who was a defensive assistant last season and was a head coach with the Los Angeles Chargers and a defensive coordinator with the Rams, would be an in-house candidate.