The NFL's war with the rival American Football League began to increase as the two leagues competed for the top players coming out of college. Prior to the season, both the NFL's Chicago Bears and the AFL's Kansas City Chiefs selected running backGale Sayers in their respective league drafts. Sayers eventually decided to sign with the NFL's Bears in a victory for the established league. On the other hand, quarterbackJoe Namath was selected by both the NFL's St. Louis Cardinals and the AFL's New York Jets, but Namath decided to play for the Jets after signing a $427,000 contract for three years. This war between the AFL and the NFL would escalate until just before the 1966 season, when they would agree to merge and create a new AFL-NFL World Championship Game between the winners of the two leagues, that later would be known as the Super Bowl.
A sixth official, the Line Judge, is added to the officiating crew. This change is sometimes referred to as the "Fran Tarkenton Rule" after the Minnesota Vikings quarterback, who developed the nickname scrambler as he ran around the backfield to avoid being sacked by the opposition. With the Line Judge stationed on the line of scrimmage opposite the Head Linesman, it made it easier for the officials to judge whether or not Tarkenton or any mobile quarterback crossed over the line before throwing the ball. Five officials had been used since, when the back judge was added.
Conference races
Each team played each of the six other teams in its conference twice. In addition, each team played two of the seven teams from the other conference to complete the 14 game schedule. Thus each week's schedule included 6 intra-conference games and one inter-conference game. In 1965 the Western Conference dominated the Eastern winning 13 out of the 14 interconference games. The lone win for the Eastern Conference was a 39–31 victory by Dallas over San Francisco in week eight. As in 1964, the Eastern Conference race started out as a battle between the Cardinals and the Browns. By Week Five, both had 4–1–0 records, but the Cards won only one more game after that, finishing 5–9. The Browns won all seven of their remaining divisional games during the same stretch, losing only their two inter-conference games against Western opponents. The Browns had clinched the conference title by November 28. In the Western race, Green Bay won its first six games before a 31–10 loss at Chicago on Halloween put it in a tie with the Baltimore Colts. In Week Eight, the Packers lost again, 12–7 to Detroit, while the Colts beat Chicago 26–21. Both teams won their next two games, but in Week Eleven, the Packers lost 21–10 to the Rams, and the Colts averted a loss by tying the Lions, 24–24. In Week Twelve, Green Bay closed the gap with a 24–19 win over the Vikings, while the Colts fell to Chicago, losing the game and their star quarterback, Johnny Unitas, to a knee injury. With backup Gary Cuozzo passing for the Colts, they met the Packers again, in Baltimore, on December 12, and Paul Hornung scored five touchdowns as Green Bay won, 42–27, to take a half-game division lead, 10–3 to 9–3–1. Along with the conference lead, the Colts lost another quarterback when Cuozzo was injured. In the final weekend, the Colts were in Los Angeles for a Saturday game that they had to win, but were losing 17–10. A tying touchdown by fourth-string quarterback Ed Brown helped the Colts knot the game 17–17, but a tie wasn't enough. It took Lou Michaels' field goal to get a 20–17 win and a 10–3–1 record. A Green Bay win the next day in San Francisco would have ended the race, and the Packers leading and were slightly more than a minute away from the title game, but the 49ers tied the game, 24–24, with 1:07 to play. Both Green Bay and Baltimore had 10–3–1 records, forcing a playoff for the day after Christmas.
W = Wins, L = Losses, T = Ties, PCT= Winning Percentage, PF= Points For, PA = Points Against Note: Prior to, the NFL did not include tie games when calculating a team's winning percentage in the official standings
Playoffs
Because the Green Bay Packers and Baltimore Colts ended up tied in the Western Conference standings after the regular season ended, a conference playoff game was held in Green Bay at Lambeau Field. Although the Packers had defeated the Colts in both of their games in 1965, there were no tiebreaking rules at the time. In the playoff game, both Colts starting quarterback Johnny Unitas and backup Gary Cuozzo could not play, so Baltimore was forced to use Tom Matte, normally a running back, as quarterback. Packer quarterback Bart Starr was injured on the first play from scrimmage and did not return to the game, relieved by Zeke Bratkowski. Green Bay's Don Chandler kicked a 27-yard field goal with less than two minutes remaining to tie the game and it went to overtime. Chandler kicked the game-winning 25-yard field goal after 13 minutes, 39 seconds of extra time. The following week at Lambeau, Starr returned and the Packers defeated the Cleveland Browns in the NFL championship game, the last before the Super Bowl era. Western Conference Playoff Game
The Playoff Bowl was between the conference runners-up, for third place in the league. This was its sixth year and it was played a week after the title game.