In the National Football League, the highest official passer rating that a quarterback can achieve is 158.3, which is considered a perfect passer rating. Thirty-five different quarterbacks have had a "perfect game" since the advent of passer ratings in 1973. Four games have occurred in the post-season. Seven men have achieved the feat more than once: Peyton Manning has thrown four, Ben Roethlisberger and Kurt Warner have thrown three, and Craig Morton, Dave Krieg, Ken O'Brien, and Tom Brady have two. Of these, only Roethlisberger has had more than one in a single regular season, when he had two perfect ratings in 2007. Johnny Unitas, Joe Namath, Terry Bradshaw, Len Dawson, Bob Griese, James Harris, Bob Lee, Craig Morton, and Eli Manning had at least one game with a perfect passer rating