Despite the Jets' shocking victory over the Colts in Super Bowl III, many people remained unconvinced that the AFL really had pulled even with the NFL. Partisans of the NFL considered the Jets' win a fluke. They fully expected the balance of power to be restored when the NFL title-winning Minnesota Vikings played the Kansas City Chiefs, losers of the first Super Bowl, in Game IV. The oddsmakers agreed; at kickoff, the Chiefs were two touchdown underdogs.
The Vikings relied on a marvelous defensive front four of Carl Eller, Alan Page, Gary Larsen, and Jim Marshall, who were nicknamed the "Purple People Eaters." Not only had Minnesota led the league in fewest opponents' points scored, but, largely because the defense kept giving the offense the ball, their ground-based attack topped the NFL in scoring.
Kansas City finished behind Oakland during the regular season before coming on strong during the playoffs. But five days before the Super Bowl, word leaked out that quarterback Len Dawson's name had been linked to a federal gambling investigation in Detroit. Although he eventually was cleared of any wrongdoing, the pressure of the investigation added to the pressure he already was under as a Super Bowl quarterback, causing him to lose sleep, weight, and concentration.
The Chiefs took the field wearing a patch on their jerseys reading "AFL-10," signifying the American Football League's 10-year existence. Super Bowl IV was the last game to be played by an AFL team.
Despite Minnesota's defensive reputation, it was Kansas City's huge defensive linemen who outmuscled the smaller Vikings on the line of scrimmage and kept Minnesota from establishing a running game. Buck Buchanan and Curley Culp outpowered Vikings' all-pro center Mick Tingelhoff to clog up the middle, and the Chiefs' linebacking crew of Willie Lanier, Bobby Bell, and Jim Lynch stopped anyone who filtered through.
Just past midway of the opening quarter, Kansas City's Jan Stenerud connected on a 48-yard field goal. He added two more field goals in the second quarter to increase the lead to 9-0. On the kickoff following Stenerud's third field goal, Minnesota's Charlie West fumbled, and Remi Prudhomme recovered for Kansas City at the Vikings' 19. On third down from the 5, Mike Garrett scored for Kansas City.
Trailing 16-0, the Vikings forced the Chiefs to punt to start the second half, then drove 69 yards in 10 plays for a touchdown. Minnesota quarterback Joe Kapp went 4-for-4 for 47 yards on the drive. With slightly more than 10 minutes of the third quarter gone, Dave Osborn scored to make it 16-7.
The Chiefs took the kickoff to their 18, moving to the Minnesota 46. Then Dawson tossed a short pass to Otis Taylor, who took the ball at the 41 and ran through Vikings cornerback Earsell Mackbee. Safety Karl Kassulke had a shot at him at the 10, but Taylor's fake left Kassulke lying on the ground and allowed Taylor to reach the endzone.
In the fourth quarter, the Vikings had three possessions, with little choice but to pass, and each possession ended in an interception. For the Chiefs, the 23-7 victory avenged their Super Bowl I loss. For the AFL, it proved it really was ready to compete evenly with the NFL. And for Len Dawson, who had survived the pregame pressure to be named MVP, the game stamped him as a great quarterback.