Alex Smith dived for a touchdown on the first possession of overtime, completing the Kansas City Chiefs’ frantic rally from a 17-point fourth-quarter deficit to beat the San Diego Chargers 33-27 in their season opener Sunday.

Smith threw for 363 yards and two touchdowns, the second a back-shoulder fade to Jeremy Maclin with just over nine minutes left in the fourth quarter that trimmed the Chiefs’ deficit to 27-17.

Cairo Santos kicked a 33-yard field goal a few minutes later, and after forcing a three-and-out, Spencer Ware finished off a four-play drive with a touchdown plunge to knot it at 27.

Kansas City needed 10 plays to march 75 yards in overtime, and Smith finished off one of the biggest comebacks in franchise history with his keeper from the 2-yard line on third-and-goal.