Rams coach Jeff Fisher informed Goff and Case Keenum of the switch when he met with the quarterbacks on Tuesday morning, sources told ESPN. Keenum, who started the team's first nine games, will be the backup, and second-year quarterback Sean Mannion will remain No. 3, for now.
"I think it's time,'' Goff said after Tuesday's practice. "I'm ready to move forward and play. I'm just going to work hard and hopefully win.''
Goff was the first pick in the 2016 NFL draft, but he made steady progress in practice during the first half of the season. Sources said the Rams' staff believed the rookie from Cal was "close" to stepping in as the starter within the past two weeks, but Keenum remained the quarterback for Sunday's 9-6 road win against the New York Jets at MetLife Stadium.
It was the third game in which the Rams' offense failed to score a touchdown, which prompted Fisher to joke Monday that his team was an "offensive juggernaut" and 2-1 in games when the Rams had not produced a TD.
The Rams' confidence in Goff is evident, as the 4-5 team remains in contention for a playoff spot. He has been getting limited reps with the first-team offense the past few weeks, including all the first-team reps during the Rams' bye in Week 8.
"He's ready, he's preparing and doing well," Fisher said of Goff on Monday. "He's anxious and confident."
Fisher has maintained that Goff would be the starter "when he's ready." Goff was inactive for Week 1, with Mannion serving as Keenum's backup; but Goff has been the No. 2 quarterback since Week 2.
"It wasn't a spontaneous decision,'' Fisher said. "It was a progression. It's a gut feel. It's not an easy thing. It takes time, and we gave it time, and it was the right decision. We're looking forward to watching him play.
"He's going to have some moments, like all young quarterbacks do, but he's going to do well.''
Even though Goff was the first overall pick, five other rookie quarterbacks have started at least one NFL game this season, in part due to unforeseen circumstances: Carson Wentz (Eagles), Dak Prescott (Cowboys), Jacoby Brissett (Patriots), Cody Kessler (Browns) and Paxton Lynch (Broncos). Wentz and Prescott have started all of their teams' games.
There is not necessarily a belief that Goff alone will solve the Rams' anemic offense, a source said. Rams running back Todd Gurley has yet to get untracked, and the offensive line play has been spotty at times. The Rams rank second worst in the league in total offense and have scored the fewest points (139) in the NFL.
Nevertheless, with Goff now fully indoctrinated into the offense after exclusively running a no-huddle spread attack during four seasons at Cal, team sources said there is hope he will energize the team and a home fan base that was hostile during the team's most recent game at the Coliseum -- a 13-10 loss to the Carolina Panthers on Nov. 6. That was the Rams' fourth consecutive loss after a 3-1 start.
Fisher said he has finally seen enough on the field -- and from Goff in practice -- to warrant the inevitable change.
"It feels like a long time since I've got out there and played,'' Goff said. "I'm excited to get back out there. ... I saw a lot of stuff from the sidelines, as much as you can see during games, and learned from a lot of the things Case did -- good and bad. It's been a long process, I guess, trying to pick up everything and get ready for it. I think I have, and I think I've been ready for a little while. I feel good, and I feel excited.''
This Sunday, Goff will face a Dolphins defensive front seven that overwhelmed the Chargers' offensive line and frustrated veteran quarterback Philip Rivers into throwing four interceptions in Sunday's 31-24 victory at San Diego. Miami is on a four-game winning streak.
The rest of the Rams' schedule after the game against the Dolphins also would present its challenges for Goff. The Rams play early games at New Orleans (Nov. 27) and at New England (Dec. 4), then host Atlanta (Dec. 11) and visit Seattle (Dec. 15, a Thursday night) before finishing with home games against San Francisco (Dec. 24) and Arizona (Jan. 1).
Information from The Associated Press was used in this report.