Pivotal Pro Football Moments
pivotal NFL postseason moment: A decision by a coach or an action by a player that establishes, continues or changes the momentum of a playoff game.
Turnovers Sink Vikings
1971 NFC Division Playoff: Dallas Cowboys @ Minnesota Vikings
The weather forecast for the Cowboys' Christmas Day visit to frigid Minneapolis was a high of 19° with a low of 11. The Dallas Times-Herald dubbed the game "Ice Bowl II." Ice Bowl I was the December 30, 1967 NFC Championship Game when the Cowboys played the Packers in below zero weather in Green Bay and lost on Bart Starr's quarterback sneak in the last minute.
Cowboys Fly in Friday
Coach Tom Landry and his staff debated whether they should fly to the Twin Cities earlier in the week to get acclimated to the cold or wait until Friday, the day before the game. He de­cided to follow the strategy of 49ers coach Dick Nolan, Tom's former assistant who had elim­inated the Vikings the year before after arriving a day before the game. The Dallas coach believed the less time spent in cold weather, the better.
Grant Starts Lee
The Vikings had a revolving door at quarterback. 30-year-old Gary Cuozzo started eight games, winning six. Norm Snead, two years older than Cuozzo, started two and won both. The youngest of the three, Bob Lee, had the strongest arm of the trio and won three of his four starts, including the 27-10 season-ending victory over the Bears.
Coach Bud Grant waited until Friday to name Lee, "the brash 26-year-old from San Fran­cisco," as his starter.
As it turned out, the weather was warmer than expected: 30° with a 9mph wind – positively balmy compared to Ice Bowl I. So much for "Vikings weather." "When I got up this morning and saw what it was like, well, I was a very happy man," said Landry.
Defense Rules First Half
With snow piled on the sidelines in Metropolitan Stadium, you'd expect a defensive battle when the top two defensive teams in the NFC meet. And that's what you got the first 30 minutes as neither team scored a touchdown.
Dallas scored first after DT Jethro Pugh recovered FB Dave Osborn's fumble on the open­ing possession of the game. QB Roger Staubach hit WR Bob Hayes for 18y to the 22. But the Purple People Eaters did what they do best. First, DT Alan Page sacked Staubach. Then DE Jim Marshall tackled Roger the Dodger short of the first down as he scrambled out of the pocket. So Mike Clark booted a 26y field goal. 3-0 Dallas

L-R: Tom Landry, Bud Grant, Bob Lee, Dave Osborn
In the second quarter, Fred Cox tied the score with a 27y three-pointer. Continuing to stifle the Dallas offense, the Vikings threatened to take the lead later in the period when Lee com­pleted a 49y pass to WR Bob Grim. But on second and 10 from the Dallas 29, the Cowboys blitzed as Lee dropped back for a screen pass. LB Chuck Howley broke through but sensing what was developing, jumped up and snagged Lee's attempt to lob the ball over his head to FB Dave Osborn. Howley returned 26y to the Vikings 37 to set up another Clark field goal, this one from the 44. 6-3 Dallas
Clint Jones returned the kickoff 61y to the Dallas 35 to give the Vikings a chance to score before intermission. He would have gone all the way except for an outstanding tackle by DB Mel Renfro. But a dropped pass and a fine breakup of a pass at the goal line by Renfro brought in Cox for a 42y field goal attempt that sailed wide.
Harris's Interception Sets Up First Touchdown
Early in the second half, the Vikings faced second and one at their 22. Lee rolled out and threw a high floating ball to Grim, who faked short, then went deep, leaving Renfro behind. But FS Cliff Harris, roving across the field, made a leaping interception and returned to the 13. "We were in man-to-man coverage," said Harris, "and I was free. I felt Grim was doing a sideline and takeoff which we'd seen before. Mel had Grim covered so I had the ball all the way."
Dallas scored from there on a perfectly executed play against the Vikings blitz. Staubach faked a quick pitch to Calvin Hill going wide left, then handed to Duane Thomas heading over right tackle. LG John Niland took out Page, allowing Thomas to veer back inside and score standing up. Dallas 13 Minnesota 3

Mel Renfro
Ed Sharockman

Roger Staubach throws a jump pass over DT Alan Page.
Cowboys Burn Sharockman Twice
Later in the third period, Staubach led an eight-play, 52y touchdown drive. The big play came on third and 15 when Roger found veteran WR Lance Alworth on the sideline for 30y to the 13.
CB Ed Sharockman, who blocked a punt and intercepted three passes against Dallas the year before, was stung on the play. "Sharockman doesn't have great speed," said Landry, "but he's real smart. He guessed wrong on Alworth."
"It was off a streak and sideline route," said Staubach. "He (Sharockman) thought Lance was going to fake a turn-in and then take off deep and that I'd try to loft the ball to him." So Sharockman turned and raced downfield like a wild man before realizing Alworth had cut to the sideline. Ed had to break, come back and make the tackle.

L: Staubach passes; R: Duane Thomas runs.
Three snaps later from the nine, Staubach hit Hayes for the touchdown. Dallas 20 Minne­sota 3 with 1:38 left in the third quarter
The scoring play was designed to go to TE Billy Truax running a turn-out route against SS Paul Krause. Staubach scrambled out of the pocket, avoided tacklers, and headed to his left. Hayes, running a down and in, stoppped when he saw Roger scrambling, then started running in the same direction as his quarterback leaving Sharockman behind. Hayes took Staubach's rifle shot at the back of the end zone.
Aided by Dallas running the ball to protect their lead, the Minnesota defense held Dallas without a first down the rest of the game.
In fact, the People Eaters scored the Vikings' next points when Page tackled Staubach in the end zone for a safety. Dallas 20 Minnesota 5
Grant Puts in Cuozzo
Since Lee hit only seven of 16 passes while suffering three interceptions, Grant put in Gary Cuozzo with 12 minutes left to play. With Dallas playing loose to avoid long gainers, Cuozzo led a seven-play 59y touchdown drive that ended with a 6y touchdown pass to TE Stu Voight with only 2:08 left. Dallas 20 Minnesota 12 (2:08)
The Vikings soon got the ball back, but Cuozzo's long desperation pass was intercepted by Herb Adderley to lock up the victory.
FINAL SCORE: DALLAS 20 MINNESOTA 12
Post Game
Coach Landry called it the best defensive performance of the season. The Vikings held Dallas to their lowest offensive production of the season (183y, 61 less than their next lowest performance). So in a sense, the Purple People Eaters did their job. But it was what they didn't do that made the difference: No turnovers compared to five for the Doomsday Defense.
References:
Breakthrough 'Boys: The Story of the 1971 Super Bowl Champion DALLAS COWBOYS, Jaime Aron (2011)