That's the way it is sometimes with coaches on opposite sides of the ball as one man hopes his unit will outshine the other man's in practice during the week.

When Lombardi left to become head coach at Green Bay in 1959 and Landry took the expansion Cowboys job in 1960, the two men were set up to become arch-rivals throughout the decade, and their teams would ultimately meet in two of the most memorable NFL championship games in history.

Linebacker Chuck Howley was one of the key performers in the Tom Landry Flex defense.(Provided to SportsLine)

Lombardi's pet play, the one that keyed the success of his great Packers teams, was the power sweep with Paul Hornung or Jim Taylor following the lead blocks of pulling guards Fuzzy Thurston and Jerry Kramer. Lombardi even wrote a book titled "Run To Daylight," which explained the basic principle behind the play.

Landry's answer was the Flex defense. "Lombardi wrote 'Run to Daylight,' and we wanted to take away the daylight," Landry once said.

Landry utilized the 4-3 defense, which he made famous during his time with the Giants, and tweaked it slightly by setting two of the four defensive linemen back off the line of scrimmage by a yard. The theory behind that alignment was that it would be easier for the Cowboys to control every gap because the two men who were set back could see what was going on more clearly.

"When you just go after the ball, bouncing off blocks, there's going to be some daylight," Landry said. "Lombardi took to Green Bay the idea of pulling a lineman to get the flow going one way, then the back would take a counter step back into the hole. But we wanted guys to hold their position, control their area, see the point of attack, then have three or four guys close in."

In the Flex, six of the front seven were responsible for one gap each. The middle linebacker, first Jerry Tubbs and later Lee Roy Jordan, would read his keys based on what the center and guards did and then with the linemen controlling their gaps and keeping blockers tied up, the middle linebacker was free to roam to the ball.

In effect, what the Flex did was take away a player's natural instincts of pursuit. The linemen were expected to control their area, not their man, and wait for the ball to come to them. This was a point Landry recognized, and he admitted the Flex probably took away from the natural skills of his players.

SPOTLIGHT

Bob Lilly(Provided to SportsLine)

"When I created the flex in about 1964, it was a completely different concept because it actually was based on engineering principles, which is why it was called the Flex," said Landry. "It took a real commitment from the players to play it because it took away a lot of natural instincts.

"It took a lot of character to play the Flex. A guy like Bob Lilly could have just pushed people off him and gone for the ball, but he didn't. And we had a great defense through the 70s. It's a defense that would still work today if the players would play it."

What helped Landry was the fact that personnel director Gil Brandt knew what types of players the coach needed to play that defense.

"By 1965, we just got more players than other teams had," said Tubbs, who later served Landry as an assistant coach for 23 years in Dallas. "Of course Gil was spending three times as much as any other team to find them, and the players we had were getting to know the system.

"Players, that's the name of the game. Lilly had turned into a terror, an unbelievable combination of quickness, agility, and strength. Chuck Howley was coming into his own, and Lee Roy was starting to play in place of me."

When the Cowboys appeared in their first championship game in 1966, the line was anchored by Lilly and George Andrie, the linebackers were Jordan, Howley and Dave Edwards, and the secondary was led by Mel Renfro and Cornell Green. That day they were carved up by Bart Starr, who threw for 304 yards and four touchdowns in a 34-27 Green Bay victory.

Jethro Pugh became a starter in 1967 and was a dominant force, though he will forever be remembered as the man Jerry Kramer cleared out of the way to allow Starr to sneak across the goal line with 16 seconds to go to win the Ice Bowl at Lambeau Field.

Through the years, players such as Larry Cole, Herb Adderley, Cliff Harris, Charlie Waters, Pat Toomay, D.D. Lewis, Bob Breunig, Too Tall Jones and Harvey Martin were plugged in, but the concept remained the same. Opposing teams simply couldn't figure out the best way to attack the Flex.

Lilly made it to the Hall of Fame playing the Flex, but he remembers thinking it wasn't going to work. "I always appreciated playing for Landry, a defensive-minded coach. But we actually started from scratch and when we went through the hard times early, there were a lot of us who didn't think his philosophy would work."

Well, from 1965-83, the Cowboys missed the playoffs only once, that in 1974, and Dallas played in five Super Bowls, winning two. During that period, the offense, directed first by Don Meredith and later by Craig Morton and Roger Staubach, was usually dynamic, but it relied on the defense to set the tone, establish field position, and ultimately keep the other team's score down.

Photos courtesy of the Dallas Cowboys