ENGLEWOOD, Colo. -- Quarterback Brock Osweiler defected from the Broncos on Wednesday, agreeing to a four-year, $72 million contract with $37 million guaranteed with the Houston Texans instead of becoming the successor to Peyton Manning in Denver.
The Broncos also offered a four-year contract, but for $64 million with $32 million guaranteed.
Osweiler, who backed up Manning for four seasons with the Broncos, was inserted into the lineup in the second half of the Week 10 against the Kansas City Chiefs after Manning was an anemic 5 of 20 for 35 yards and four interceptions with a 0.0 quarterback rating.
Osweiler started the next seven games as Manning recovered from a torn plantar fascia in his left foot, going 5-2.
But in the regular-season finale against the San Diego Chargers, he had two interceptions and the Broncos had five turnovers overall as their chances of gaining home-field advantage throughout the AFC playoffs were slipping away.
Coach Gary Kubiak yanked Osweiler at halftime and reinserted Manning into the lineup, and he helped the Broncos come back to win, 27-20.
Manning then got the starts in the home playoff wins over the Pittsburgh Steelers and New England Patriots, and was the starter in the 24-10 win over the Carolina Panthers in Super Bowl 50.
Manning on Monday announced his retirement and the Broncos been grooming Osweiler to be his replacement since they drafted him in the second round in 2012. But he instead, bolted for Houston on the first day of free agency in the NFL.
"We stayed true to our philosophy of building a team with players who want to be Denver Broncos and want to be here. That's been a successful approach for us," Broncos Executive Vice President of Football Operations and General Manager John Elway told the team's website.
"We've now turned out attention to other options at quarterback and are confident we'll find the right player and person for our team. Our organization thanks Brock for his contributions and wishes him well."
Osweiler, who arrived in Houston on Wednesday night to sign the contract, took to social media to thank Broncos fans for his time in Denver.
The loss of two quarterbacks in three days sent the Broncos into Plan B mode as they scramble to find a replacement for next season as they defend their Super Bowl title.
Trevor Siemian, a seventh-round draft pick last year, is the only quarterback on the roster, but he has taken only one snap.
The Broncos are expected in inquire about San Francisco 49ers quarterback Colin Kaepernick, who has requested a trade after being benched last season. But the 49ers said they do not intend to trade Kaepernick, who had thumb and knee surgeries.
Robert Griffin III is on the market after getting cut by the Washington Redskins, but he has not started since 2014 and was inactive all of last seasons after being passed by Kirk Cousins and Colt McCoy.
Griffin is injury-prone and is 5-15 in his past 20 starts after having a strong rookie season with 20 touchdowns and only five interceptions under coach Mike Shanahan.
Ryan Fitzpatrick is also on the free agent market after throwing 31 touchdowns with the New York Jets last season, though he's expected to stay with the AFC East team.