Janikowski's kick cleared the crossbar as the second quarter expired, giving the Raiders a 16-3 lead.
That tied the longest field goal in NFL history. Tom Dempsey set the mark for New Orleans in 1970 and Denver's Jason Elam matched it in 1998.
The Raiders got the ball with just 24 seconds left when Matt Giordano intercepted a pass thrown by Kyle Orton.
A 15-yard facemask penalty on Broncos defensive tackle Kevin Vickerson put the ball near midfield and Jason Campbell's throw to Marcel Reece moved the Raiders to the Denver 45 and put Janikowski within range of history.