Blaine Gabbert will start at quarterback for the San Francisco 49ers against the Atlanta Falcons on Sunday.
Widespread reports that the 49ers had run out of patience with under-performing Colin Kaepernick were confirmed by coach Jim Tomsula at his press conference on Wednesday.
Kaepernick has struggled badly for most of the season, and has only been able to engineer two wins from San Francisco's first eight games.
"I met with the quarterbacks on Monday and made the decision to go with Blaine Gabbert," Tomsula said.
"It was a tough decision, but I feel it's the direction we need to go.
"I want Colin to step back and breath and look at things through a different lens. He will keep preparing and keep doing his thing."
Gabbert was drafted with the 10th pick of the 2011 NFL draft by the Jacksonville Jaguars, and he played in 29 games for the franchise before being traded to the 49ers in March 2014.
He was efficient in pre-season, completing 23 of his 28 pass attempts, but Sunday's game with the Falcons will mark his first regular season action for more than a year – he threw seven passes, one of those going for a touchdown, against the Broncos in October 2014.
"Blaine has been here for two years and I've watched Blaine get here better every day," Tomsula added. "I've watched the way he goes about his business. I've watched the ball that he throws. I watch how he practices. I watch his seriousness and the way he's prepared every week since he's been here. He's a competitive guy."