Fifteen long weeks ago, the Minnesota Vikings took on the Dallas Cowboys. Tony Dorsett played little and Francis Tarkenton went all the way. Final score: Dallas 16, Minnesota 10, in overtime.

Now these same teams meet again for the NFC championship at Texas Stadium Sunday (WTOP-TV-9 at 5:30 p.m. EST). Tony Dorsett will start, and probably finish, for the Cowboys. Tarkenton, the wounded Viking quarterback, will watch from home in Atlanta.

Final score? The oddsmakers say the Cowboys are 11-point favorites to advance to the Super Bowl, the season-ender the Vikings have lost four times in the last seven years.

Clearly, the Cowboys deserve that sort of support. They played The Perfect Game last week in routing the Chicago Bears, 37-7, and coach Tom Landry says his team is primed for a repeat performance.

Dorsett, who gained only 11 yards in four carries against the Vikings in the season opener, went on to pick up 997 yards the rest of the way. "He's making a real contribution now," said Landry, master of understatement.

Quarterback Roger Staubach is directing the NFC's No. 1 offense and throwing the football as "well as I've thrown in a long time."

The Cowboys ran for 233 yards against the Bears, and should be able to move it by land against a Viking defense ranked 11th in the conference against the rush, despite that new odd-man defensive line that was supposed to stop opposition backs.

The Cowboys' flex defense also is designed to stop folks like Chuck Foreman, the Vikings' all-purpose, multi-talented running back. Last week, Dallas held the best Bear, Walter Payton, to 60 yards in 18 head knocking carries.

Our players know what the playoffs are all about," said Viking coach Bud Grant. "They prepare themselves emotionally, they know what it takes."

The Vikings are among the oldest teams in the NFL, averaging eight years per man in experience on the starting 22.

The offense will be directed by Bob Lee, 32-years-old journeyman quarterback who will remind no one of Tarkenton. He threw for 206 yards against the Lions in a game the Vikings had to win to earn the NFC Central title. And he played a major role in that sloppy victory over the Rams.

Lee throws to two talented wide receivers, Ahmad Rashad (51 catches) and deep threat Sammy White, who averaged 18 yards for each of his 41 receptions. In Foreman, the Vikings have one of the game's least-publicized superstar running backs.

Foreman ran for 1,112 yards and caught 38 passes in 1977, with nine touchdowns.

The Vikings bend like so many rubber bands on defense, but always seem to snap back against the pass. They ranked third in the NFC in pass defense.

Staubach killed the Vikings with a four-yard touchdown run in overtime, and completed 18 of his 30 passes for 166 yards, no interceptions and only two sacks.