Gore was involved again at the start of the season, powering his way through midfield to set up Adam Vinatieri for a field goal, while the Colts got the ball back a couple of plays after as Mike Adams picked off a pass from Peyton Manning, giving the quarterback his 12th interception of the season.
Denver's comeback continued at the start of the third quarter as Manning spotted a run from Emmanuel Sanders, launching the ball 64 yards down field for the wide receiver to sprint in for the touchdown.
Manning tried to find his receivers again, with Owen Daniels picking up 37 yards before being forced out of bounds, while Demaryius Thomas came up short looking for the touchdown, leaving Brandon McManus to tie the scores with a field goal.
Luck responded, spotting Ahmad Bradshaw wide open on third down, tossing the ball forward for the running back to burst across, restoring the home side's lead.
As the second half progressed Manning closed in on the NFL's all-time passing record, aided by Thomas and Daniels hauling in big gains again, with the latter snatching a one-yard touchdown pass, leaving the quarterback needing just three more yards to beat the record currently held by Brett Favre.
The Colts were able to get into Vinartieri's field-goal range again on their next possession, leaving Denver heading back onto the field knowing that a touchdown would hand them the lead for the first time.
However, Manning's first pass went straight to Darius Butler for an interception, allowing the Colts to keep the ball for the rest of the game, preventing the Broncos quarterback from making another completion to break the record and continue the team's unbeaten start to the season.
The result keeps the Colts at the top of the AFC South with a 4-5 record, while the Broncos stay top in the AFC West, having won their first seven games of the season.