DENVER, CO - DECEMBER 12: Keenan Allen #13 of the San Diego Chargers scores a second quarter touchdown against the defense of Kayvon Webster #36 of the Denver Broncos at Sports Authority Field at Mile High on December 12, 2013 in Denver, Colorado. (Photo by Justin Edmonds/Getty Images)
Mike McCoy's gamble paid off big-time.
San Diego's coach outfoxed his mentor John Fox and handed his former pupil Peyton Manning his first divisional loss since coming to Denver as the Chargers stunned the Broncos 27-20 on Thursday night.
McCoy bucked conventional wisdom and give Manning the ball first, deferring after winning the coin toss.
It seemed like a huge mistake when Manning, who entered the game with 45 TD throws as leader of a high-octane offense that was scoring nearly 40 points a game, needed just seven plays to put the Broncos ahead 7-0.
Before long, Manning had Denver up 10-3.
But then, the Chargers held the Broncos to just 13 yards on their next 13 plays covering nearly 30 minutes of game clock, allowing just one first down and forcing Manning to go three-and-out three times.
Meanwhile, the Chargers were chewing up yards and clock on their way to winning the time of possession by an astonishing 17 minutes, 38 seconds.
And San Diego's win sent ripples through the AFC playoff picture.
The Chargers (7-7) are now in the thick of the wild-card race with their second win in four days over a Manning brother -- they eliminated the New York Giants from the NFC playoff race Sunday with a 37-14 win over Eli's team -- and the Broncos (11-3) were left to sweat out the long weekend.
Now, the New England Patriots (10-3) can surpass them in the race for the top seed in the AFC with a win over Miami and the Chiefs (10-3) can tie them atop the AFC West again, although the Broncos own the tie-breaker there.
Philip Rivers threw two TD passes to rookie Keenan Allen in the first half and Nick Novak kicked a 38-yard field goal, giving the Chargers a 17-10 lead at the break.
The Chargers cashed in on their coin-toss deferment when they drove right down the field again and Ryan Matthews slipped Von Miller's tackle for a 23-yard TD on San Diego's opening drive of the third quarter to make it 24-10.
Even when they were backed up at their 1, things went right for San Diego.
Lined up to punt out of their own end zone on fourth-and-4 from their own 7, the Chargers got Broncos linebacker Nate Irving to jump into the neutral zone.
Instead of giving the Broncos the ball back at midfield midway through the third quarter, the Chargers ran off another seven minutes before finally punting.
Manning drove Denver 89 yards and pulled the Broncos to 24-17 with a 5-yard TD toss to Bubba Caldwell with 10:25 left.
Manning got the ball back at his 3 with a chance to tie it with a long drive, but linebacker Thomas Keiser intercepted his deflected pass at the Denver 33, leading to Novak's 35-yarder that made it a 10-point game with 2:36 left.
The Broncos' last drive stalled at the 24 and Matt Prater's 42-yarder made it a one-touchdown game but he couldn't execute the onside kick with 29 seconds left and Rivers took a knee.
The Broncos ran just 53 plays, only 11 of them runs, a week after taking 91 snaps against Tennessee in much colder weather.
The Broncos have been held under 30 points just three times all season, twice by the Chargers, whom they beat 28-20 last month when Jack Del Rio was in charge while Fox was recuperating from heart surgery in North Carolina.