The Monday afternoon phone call to Las Vegas was not necessary this week. Instead, Vegas called Washington late Monday morning volunteering the line on Sunday's games.

There was, naturally, an ulterior motive for the call.

"We're a little surprised," the voice from afar admitted. "We just got the service line, and the Cardinals are 2 1/2 points over the Redskins Sunday in Washington.

What happened? Is somebody important on the Redskins injured and nobody knows about it?

I dialed the sports desk of The Washington Post in search of inside information for the seeker of truth in Nevada and was informed that, yes, there had been a serious injury following Washington's 10-6 victory over Atlanta Sunday.

I called Las Vegas and told an aide to the gentleman who had phoned me that morning that there was a late Washington injury.

"We thought there had to be," the aide said. "There had to be a reason we got the number we did.

"Who is it?"

"It's Asher," I replied.

There was a pause in the conversation. The man on the other end of the line was puzzled, but equally determined not to display the slightest sign "How bad is Asher hurt?"

"It's his left foot," I answered. "In the Atlanta game he tripped in the dugout on the way to the locker room and broked his foot. It's in a light cast. They say he'll be out anywhere from four days to four weeks."

"O.K." the teller in the sportsbook said, "Thanks for the help."

I could just imagine the flurry of excitement on the big boards along the Strip as the word spread through the desert dugouts of the Asher injury.

Twenty minutes later the phone rang again. It was another call from Numbersville. Only this time it was "The Boss."

"Who," The Boss wanted to know, carefully selecting one word at a time, "is" - there was another short silence - "Asher?"

I told him Mark Asher is the man who, along with Len Shapiro, covers the Redskins for The Post and that his injury was the only one Washington had suffered over the weekend. It would not, however, be listed on the NFL's medical bulletin to be issued Tuesday. Asher, determined to play hurt if need be, considered himself a "probable" starter Sunday.

But Asher's boss, perhaps taking a lesson from the coach at Redskin Park, was playing it coy. "We're calling Asher doubtful for Sunday in our weekly injury report to the Pro Football Writers Association," said the sports editor. "But we have until 12:15 p.m. Sunday to make a final decision on Asher.

The possibility exists that we could activate another scribe, and put Asher on injured reserve: or we may follow a recent pattern and activate Shirley Povich and Bob Addie on Sunday for their leadership qualities."

The Las Vegas Boss was not amused, which goes to show the humor quotient of professional gamblers.

Predictably, Asher's impact on the national beting line has been minimal. The Cardinals are now three-point favorites because (1) their defense has improved. (2) Jim Hart figures to have five seconds to pick out a receiver every time he drops back to pass, and (3) Mike Thomas still appears to be too pooped to pop into the open on those are occasions when Washington's offensive line creates some crawl space.

What is "Playing Football" to do confronted by such an overwhelming mass of evidence in the Cardinals' favor?

Why, play the Redskins of course - a half-unit ($500). Cardinal coach Don Coryell, once a brash, refreshing whiff of explosive offensive planning, has become more conservative with each passing season. St. Louis was shut out by Denver's superb defense, then failed to blow Chicago out of its home park last week after leading by 16.3.

The Cardinals are having difficulties sustaining their drives inside an opponent's 20-yard line. If the problem persists, Washington will win. All the other considerations, the intangibles included, accrue to the Redskins. The old boys are not dead yet.

Elsewhere, Miami, giving five, is worth a half-unit ($500) at home against Houston. The thought of the Oilers' Dan Pastorini leading an offense against a Don Shula defense makes me smile.

San Diego, getting seven at home against Cincinnati, also attracts a half-unit ($500).The Charges should score 24 points or more.

Atlanta's defense giving but three points to the Giants in Georgia gets a quarter-unit ($250), as do the Steelers giving 4 1/2 (down from six) at Cleveland. Greg Pruitt will not run against Pittsburgh.

I am 17-11 overall against the spread this NFL season. For those fo you who must have action every-where again this week I suggest Buffalo getting 14 1/2 (out from 14) at Baltimore, Denver giving 12 at Seattle, Green Bay getting 12 at Minnesota, New England giving 13 to the New York Jets, New Orleans getting nine at Chicago, Detroit giving seven to Philadelphia, Los Angeles giving 13 to San Francisco, Dallas giving Tampa Bay 23 (in from 24) and Oakland giving Kansas City 13 1/2 Monday night.