August 8, 2013 Updated: August 8, 2013 at 10:20 pm
SAN FRANCISCO (AP) - On this first night of the exhibition season, Denver displayed the opportunistic defense the 49ers lived by the last two years, something that carried San Francisco back to the Super Bowl in February, 18 years after capturing their fifth championship.
The NFC champion Niners? They looked sloppy in all phases in 10-6 loss Thursday night.
A Super Bowl preview in August? Hardly looked that way.
Shaun Phillips scooped up D.J. Harper's second-quarter fumble and returned it 9 yards for the game's lone touchdown. Mike Adams added a timely interception as the Broncos began anew following that stunning double-overtime loss to the eventual Super Bowl champion Baltimore Ravens back in January's AFC divisional playoffs.
Executive John Elway has vowed the playoff disappointment will fuel his team.
With the star quarterbacks on either side - Broncos veteran Peyton Manning and third-year pro Colin Kaepernick - playing all of one series each, it was impossible to gauge just how good their given offenses will be.
This truly was a typical preseason opener for what many consider the best two teams in the NFL; San Francisco and Denver are 1-2 in the AP Pro32 NFL power rankings.
Now, everybody realizes that if they were to play a meaningful matchup it could really be something.
Kaepernick completed all four of his passes, two to Anquan Boldin in his 49ers debut after being acquired in a trade from the Ravens. Manning was 2 for 4 for 13 yards.
The 49ers kicked off their "Farewell to Candlestick" season before they move into their new stadium next to team headquarters in Santa Clara in 2014. Fittingly for nostalgia's sake, sprinkled among those suddenly top-selling No. 7 Kaepernick jerseys were some tributes to the old-school favorites: Joe Montana, Jerry Rice, Ronnie Lott.
New 49ers kicker Phil Dawson made field goals of 32 and 38 yards, but missed wide left on the final play before halftime with the flags whipping on a cool summer evening by the bay.
Kaepernick begins his first full season as the starter after taking the job from Alex Smith last November and leading San Francisco to the Super Bowl. And the Niners head to Kansas City for next Friday's game - against the Chiefs' new play caller, Smith.
A.J. Jenkins, one of Kaepernick's key targets, had a forgettable preseason debut.
Jenkins faces high expectations after the first-round pick went without a catch in his highly scrutinized rookie season. The 49ers are depending on him to produce while top 2012 wideout Michael Crabtree spends much of the season recovering from surgery on his torn Achilles' tendon, and Mario Manningham works back from knee surgery.
Only two plays after Phillips scored midway through the second quarter, Jenkins caught an 11-yard pass from Scott Tolzien and fumbled. Denver's Rahim Moore recovered.
A pass by Colt McCoy intended for Jenkins late in the first half was well overthrown and strong safety Adams easily grabbed the interception against his former team.
49ers first-round draft pick Eric Reid had six tackles in his professional debut.
Broncos backup quarterback Brock Osweiler completed his first six passes and went 13 for 18 for 105 yards.