There is a law, Murphy's, often invoked by bettors who have experienced a disastrous weekend. It states that everything that possibly could have gone wrong, did. Murphy's is a law for losers. I will have none of it.

That would be too easy, too convenient, too obtuse. Instead, I'll open by immediately acknowledging that "Playing Football" went 1-6 last weekend and dropped an imaginary $2,250. I will, however, apologize for only one of the selections: Washington.

Somehow, some way, San Diego and Buffalo were shut out Sunday and Miami couldn't score more than a field goal Monday night. I backed all three favorites. They have three of the most potent offenses in the NFL, and they accumulated a stirring, collective total of three points.

So much for the Lost Weekend. I have to suffer through at least one such experience each year. let us hope it will be the last for 1979.

This week, and most of the future weeks, will be different in that fewer games will be played. The risk, however, will be higher. The first four to six weeks of each season are equivalent to a shakedown cruise. From this point on, the emphasis will be on the stronger teams involved in important games when, whenever possible, they are playing at home.

Dallas, giving 4 1/2 points in Texas Stadium Sunday against Los Angeles, is a good example. The Cowboys will need a victory to stay atop the NFC East, they are healthy, and the Rams are probably the second-best squad in the conference. Dallas, confronted with such a situation, will be ready.

The Cowboy management should be commended for having brought John Dutton from exile. The former Baltimore defensive end, properly motivated, is exactly what Dallas has needed since Too Tall Jones took up boxing. Dutton will enable Harvey Martin and Randy White to look better than they are, just as Jones did.

Until Dutton is ready, however, the Cowboys will survive nicely with their offense. Roger Staubach is having his finest season. Tony Dorsett is in beautiful form and the blocking up front is excellent. Pittsburgh is the only other offense in the NFL to offer as much talent and balance as Dallas.

The Rams' defense is tough, currently superior to that of the Cowboys, but there is no comparison between the two teams offensively. And I always have confidence that the Rhodes scholar, Pat Haden, will do something stupid as the L.A. quarterback under pressure. I'll take Dallas, giving the 4 1/2, for $1,000.

The week's other prime pick is Kansas City, giving two points at home Sunday to Denver. The Chiefs' young defense has been one of the biggest surprises of the season, rookie quarterback Steve Fuller is gaining confidence rapidly and the KC. running game is underrated.

Denver's defense was marvelous in blanking San Diego. But the Broncos rarely put on such a show on the road and their offense, on its best day, sputters.

A few weeks ago, I selected Tampa Bay to beat Los Angeles because it figured to be "the game of the year" for the Bucs. This figures to be the high point of the season for Kansas City, which is tied with Denver and San Diego for first place in the AFC West at 4-2. K.C. is worth $1,000.

The only other 'pick is the New York Jets Monday night at home against Minnesota. The Jets know how to score. The Viking defense is very vulnerable. I'll give the 6 points for $250.

Other games this week on the Las Vegas line show Cleveland 3 1/2 over Washington, Tampa Bay 6 1/2 over New Orleans, St. Louis 2 over Philadelphia, Pittsburgh 7 1/2 at cincinnati, the New York Giants 5 over San Francisco, Miami 7 over Buffalo, Houston 4 1/2 at Baltimore, New England 4 at Chicago, Green Bay 3 over Detroit, Oakland 4 over Atlanta and San Diego 7 1/2 over Seattle.