INDIANAPOLIS -- Two days after celebrating their biggest win of the season, the Indianapolis Colts dealt with their biggest loss.
Franchise quarterback Andrew Luck is expected to miss at least two to six weeks with a lacerated kidney and a partially torn abdominal muscle, injuries he sustained late in Sunday's victory over Denver.
"When you take a hit to a franchise quarterback, it is a tough blow," coach Chuck Pagano said Tuesday. "We've been through a lot in this 2015 season, but I know this will galvanize us even more."
Pagano said he believed Luck was injured in the first minute of the fourth quarter when he tried to scramble for a first down near the Denver goal line. Linebacker Danny Trevathan squared up on Luck from the front while defensive end Vance Walker hit Luck hard on the side of his left shoulder, bending him over awkwardly.
The hit drew immediately drew gasps inside Lucas Oil Stadium. But Luck broke the 17-17 tie on the next play with an 8-yard pass to Ahmad Bradshaw, his second TD throw of the game. He never came out and continued to take some big hits.
Afterward, Pagano said, Luck complained of soreness. When he arrived at the team complex Monday feeling worse, Luck was sent for additional tests that revealed the injuries. Luck is not expected to need surgery. He was not available in the locker room Monday and did not mention any potential injury in his postgame news conference.
The six-week timetable could be aggressive because the Colts will be cautious about bringing Luck back.
"We're going to keep listening to the doctors and evaluating his progress on a week-by-week basis," Pagano said. "We've got all the confidence in the world in Matt Hasselbeck and we're not going to put Andrew back out there until he's healed and ready to go."
The timing couldn't be worse for Indianapolis (4-5), which was hoping to return form this week's bye and build momentum with a favorable schedule. Instead, one week after firing offensive coordinator Pep Hamilton and replacing him with Rob Chudzinski, the Colts are now forced into making a quarterback change.
The 40-year-old Hasselbeck takes over, as he did last month when Luck missed two games with an injured right shoulder. Hasselbeck won both.
Indy took another precaution Tuesday by bringing former Monmouth quarterback Alex Tanney back to the practice squad. He spent three weeks in Indy earlier this season, none of it on the active roster. Luck, Hasselbeck and Tanney are the only quarterbacks on the team after Indy released former Wisconsin-Whitewater star Matt Blanchard from the practice squad Tuesday.
"We've got all the confidence in the world in Matt," Pagano said. "Matt will step right in, he will do a great job and we will win football games with Matt."
Hasselbeck was 48 of 76 with 495 yards, three touchdowns and no interceptions in his only action this season, and having a bye week to work with Chudzinski could help make the transition smoother.
Playing behind a struggling offensive line has taken a toll on the Luck this season.
He missed the first two games of his four-year career after getting hurt at Tennessee on Sept. 27. When Luck did return, he still didn't look right. Then last week, he was listed on the injury report with a bad ankle. He started, finished and won Sunday's game, looking more like the promising young quarterback that people expected.
There has been speculation about possible fractured ribs and a more serious shoulder injury than the Colts first acknowledged.
"We will overcome this and Andrew will make a full recovery and he will be back in the lineup at some point," Pagano said. "But we will overcome."
In the AFC South, the league's worst division, Indy still holds a one-game lead over Houston and has a capable backup to run the show until Luck returns.
"It is one heck of a blow," Pagano said. "You don't want to lose anybody. Our guys will respond, like they always do. We've been through a ton already this season and in the past and we'll get through it."
Notes: Colts players were off Tuesday and won't return to the team complex until next week. ... Indy made two other practice squad moves Tuesday, signing safety Dezmen Southward and releasing offensive lineman Kitt O'Brien. Southward grew up in Indianapolis and played 18 NFL games before being waived by Atlanta last week. It could be a safety net for Indy after Pro Bowler Mike Adams went down with an ankle injury in the first half of Sunday's game.