In the third quarter of the AFC championship game, Peyton Manning did something he almost never does: He ran. For several yards.
You didn't see it coming. Neither did the New England Patriots.
Manning, the quarterback whose career is supposed to be on its last legs, used his legs to pick up 12 precious yards and a first down.
Later in the broadcast, CBS made a claim that seemed as unbelievable as Manning's run was unexpected. Old Man Manning, the network said, reached a peak speed of 17 mph.
That rickety, statuesque quarterback? The one who has had four neck surgeries? The one who suffered a torn plantar fascia in November? He did that? In pads? At 39 years old?
We'll tell you the answer.
But first, let's marvel at the rarity of what we witnessed.
• In a career that has spanned almost 300 games, Manning has gained at least 12 yards on a run just 18 previous times. Carolina Panthers quarterback Cam Newton, his counterpart Sunday in Super Bowl 50, has gained at least 12 yards on a run 14 times this season.
• Manning's run against the Patriots was his longest of the season and his longest since he ran for 27 yards on Dec. 26, 2010. On that day, Manning was wearing an Indianapolis Colts uniform, and Tim Tebow was the quarterback who led the Denver Broncos in a fourth-quarter comeback.
• In the playoffs, Manning gained double-digit yards on just one other run — a 15-yard touchdown scramble against the Tennessee Titans in January 2000. Eleven days later, President Bill Clinton delivered his final State of the Union address.
After CBS noted Manning's speed, disbelief flooded Twitter timelines.
We were skeptical, too. So we sought out how CBS came up with its precise number.
In 2014, the NFL started installing nickle-sized radio frequency identification chips developed by Zebra Technologies under most players' shoulder pads. The chips emit signals 15 times per second to receivers mounted in stadiums, transmitting data that helps determine how fast a player is running, where and how far. In 2014, 17 stadiums used the technology; by the start of this season, every stadium was equipped.
Television networks have near-instant access to the data, which they use occasionally for on-air graphics. In time, teams might use the data to inform game strategy and scouting.
We wanted to check the math on the broadcast the old-fashioned way, so we reached out to John Eric Goff, professor of physics at Lynchburg College in Virginia and author of Gold Medal Physics: The Science of Sports.
Goff downloaded video of the play formatted at 30 frames per second and analyzed it frame by frame. To gauge the accuracy of CBS' meter, he focused on the portion of Manning's run where he ran parallel to the sideline.
He found it took Manning 0.53 seconds to run from the 23-yard line to the 27-yard line, or 7.55 yards per second, which converts to an average speed of 15.44 mph.
But what about Manning's maximum speed in that span? As Manning approached each yard marker, Goff noted the elapsed time. (Because Goff was working off the broadcast camera angle, he estimated the error in his model is 10 percent or less.)
"That process allows me to find his speed at each instant in time, instead of the average speed," he said. "Your speedometer gives you instantaneous speed, not average speed."
Anyone want to talk about sixth-order time polynomials and velocity components?
Okay, then the bottom line is this: According to Goff's calculations, Manning hit 16.35 mph in that 4-yard span.
For reference, Usain Bolt, recognized as the world's fastest man, reached 27.79 mph during his record 9.58-second 100-meter run in 2009. Panthers receiver Ted Ginn, arguably the NFL's fastest man, passed 22 mph on a 74-yard touchdown against the Atlanta Falcons in December (peak speed of an actual panther: about 35 mph).
So it turns out that as unbelievable as it seemed at the time, CBS' speedometer measure of 17 mph was, in Goff's view, about right.
"Even though when he ran that play, Manning was exactly two months shy of his 40th birthday, a great 6-foot-5 athlete like him with a long stride length can, if only for a split second, sneak into 16-mph to 17-mph speed range with pads on and huge, younger guys chasing him," he said.
At the very least, this should make those of us who boast we could jump off the couch and outrun Peyton Manning feel a little less confident.
A more realistic bar: Dwight Schrute of The Office fame hit 13 mph when running past a radar speed sign.
Contact Thomas Bassinger at email@example.com. Follow @tometrics on Twitter.