Coming off their dominating divisional road win over the Raiders, the Broncos played their Week 2 home opener against the AFC West foe, the San Diego Chargers.  In the first quarter, Denver was first out of the gate as FB Michael Pittman got a 1-yard TD run.  The Chargers would respond with kicker Nate Kaeding getting a 34-yard field goal.  In the second quarter, Denver replied with QB Jay Cutler completing a 3-yard and a 14-yard TD pass to TE Tony Scheffler.  San Diego would immediately respond with RB Darren Sproles returning the kickoff 103 yards for a touchdown, yet the Broncos replied with rookie kicker Matt Prater getting a 52-yard field goal.  The Chargers would strike as their lead as QB Philip Rivers completed a 48-yard TD pass to WR Chris Chambers, yet Denver retaliated with Cutler completing a 6-yard TD pass to WR Brandon Marshall. In the third quarter, San Diego started to rally as Rivers completed a 15-yard TD pass to Chambers, and Kaeding kicked a 21-yard field goal. In the fourth quarter, the Chargers took the lead with Kaeding's 28-yard field goal and Rivers' 66-yard TD pass to Sproles. Fortunately, the Broncos responded with a 12-play, 80-yard drive (which included a controversial officiating call that turned a Cutler fumble into an incomplete pass) that was capped off with Cutler's 4-yard TD pass to rookie WR Eddie Royal, followed by Cutler's successful 2-point conversion pass to Royal. Brandon Marshall's 18 receptions would become a single-game franchise record and tie for 2nd most in league history.
Question: How many yards was the shortest field goal?
Answer: 21