Steve Young explains that if Lamar Jackson can overcome his biggest challenge yet in the Chargers' defense, the Ravens can make a deep run in the playoffs. (0:47)

LOS ANGELES -- John Harbaugh will remain the coach of the Baltimore Ravens for the 2019 season and possibly beyond, a strong vote of confidence the night before Saturday's pivotal game against the Los Angeles Chargers.

The Ravens announced Friday night that they are working on an extension to Harbaugh's existing contract, which expires after the 2019 season. This will presumably be a multiyear extension instead of the one-year deal Harbaugh received before the start of the 2017 season.

The surprise and unusually timed announcement ends speculation that the Ravens were prepared to fire Harbaugh if the team failed to make the playoffs this season. After reaching the postseason in Harbaugh's first five seasons, Baltimore has missed the playoffs in four of the past five seasons.

Harbaugh, 56, was expected to be a top candidate for other vacancies had Baltimore parted ways with him. The winningest coach in Ravens history, he has a 112-77 record (including playoffs), guiding the team to a Super Bowl title in 2012.

Retaining Harbaugh sends a strong message of approval for how the Ravens have responded since the bye.

Harbaugh and his staff built a successful and innovative offensive system around rookie first-round pick Lamar Jackson and have put the defense in position to finish with the No. 1 ranking for only the second time in franchise history.

In winning four of their past five games, the Ravens (8-6) can clinch a postseason spot if they win out. But Baltimore can be eliminated this weekend if it loses to the Chargers and three teams (Steelers, Colts and Titans) all win.

Harbaugh was considered to be on the hot seat a month ago after Baltimore had lost three straight games heading into its bye and Joe Flacco was sidelined with a hip injury.

Asked several times about his job security, Harbaugh took everything in stride.

"It's just noise. It doesn't matter. It means nothing," Harbaugh said in November of reports about his pending end in Baltimore. "It's not something that I'm going to think about or concern myself with. Neither are the players, neither is Steve [Bisciotti, team owner], neither is Kevin [Byrne, executive vice president of public & community relations] or Ozzie [Newsome, general manager] or anybody else. You know what we want to do as an organization? We want to win. That's what we want to do. We want to win. We're fighting as hard as we can -- coaches, players -- as an organization to win. That's it. All the other stuff -- who cares?"

Harbaugh has received criticism for his team's run of mediocrity in recent years. Since winning the Super Bowl, Harbaugh is 48-46 and the Ravens haven't won an AFC North title.

But the Ravens have never unraveled completely either. Baltimore has only one losing season under Harbaugh (5-11 in 2015).

One strong factor was how Harbaugh never lost the respect of the locker room.

"This team believes in him," safety Eric Weddle said last month. "We have his back."

The Ravens remain one of the most stable franchises in the NFL. Harbaugh is only the third coach in the team's 23-year history.

Among active NFL coaches, Harbaugh is the fifth-longest tenured with the same team. Only Bill Belichick, Marvin Lewis, Sean Payton and Mike Tomlin have been with their teams longer than Harbaugh.