Manning, 36, said he was given the opportunity to keep the starting streak alive but was told Smith and rookie Davis Webb would see action over the next five games regardless, via New York's team website.
Manning, 36, has started for the Giants 210 consecutive times, the second-longest stretch by a quarterback in National Football League history since Bret Farve's recorded 297 starts, according to the team's website.
Smith signed with the Giants in the offseason after playing with the Jets for his entire career.
For the first time in more than 13 seasons, the Giants will not be starting Eli Manning as their quarterback on Sunday. This is one of those things to me that you need to start Eli with the idea of we're going to try to win every game. McAdoo added that Manning would back up Smith against the Raiders. Webb is a rookie third-round pick from Texas Tech.
"I don't know, I don't know", he said quietly.
"Coach McAdoo told me I could continue to start while Geno and Davis are given an opportunity to play", said the two-time Super Bowl Most Valuable Player. For now, all we know is that Manning was benched for Geno Smith. Mara will lose all credibility if he lets Eli take the fall on his own when the coach and the GM have failed miserably in this 2-9 season that can easily be 2-14 by the time it's over.
Giants name Geno Smith as their starting quarterback for Week 13
Manning, as he spoke to reporters Tuesday, was asked whether he believes he has played his final game for the Giants.
In terms of this being the hardest day that Manning has had with the Giants, the youngest Manning brother replied: "It's up there". "We're on the same page", McAdoo said repeatedly, refusing to go into specifics.
"Coach Mac called me in", Manning said.
Best of luck to Smith, but who would've thought at the beginning of the year that Smith would be chosen to start a game over Manning, the best quarterback in franchise history?
Even though McAdoo did not rule out that Manning could be the quarterback next year, it will not likely be his decision to make. The team appears in disarray on McAdoo's watch.
Manning will not be fully appreciated until he is gone, which is happening much earlier than either he or the Giants anticipated.More news: BoE: Major UK Banks Clear 2017 Stress Test