In his football team's hour of greatest need. George Allen has decided to start Billy Kilmer at quarterback Saturday against the St. Louis Cardinals, The Washington Post his learned.

While no one at Redskin Park would say so publicly, team sources said yesterday that Kilmer has been getting a major portion of the work ahead of Joe Theismann, in the team's three closed practices this week, including the 2 1/2-hour workout yesterday.

Those same sources said the decision already has been made to start Kilmer.

"It's the same situation," Allen snapped when asked who would start at quarterback. "They'll both be ready like they've been all along. I'm not going to say who I'm going to start.

"I won't say Bill Brundige (who has a sprained foot) will start because I don't know. We were treating Brundige in his home at 11 o'clock last night. That's how desperate we are There is no tomorrow."

That also is why Allen wants to start Kilmer ahead of Theismann against the Cardinals in a game the Redskins must win to stay in the race for the NFC's wild card playoff berth.

Theismann and Kilmer referred questions back to Allen.

Kilmer has been in this situation before, and performed admirably. It was Kilmer who led the Redskins in their memorable stretch drive a year ago, taking over at quarterback for four straight victories in the final month of the regular season.

Now, after riding the bench and not throwing a pass in the last six games, Kilmer is being asked to come through again.

There are other factors involved in Allen's itch to switch, one of the foremost being the offense's inability to score consistently since Theismann took over six weeks ago.

With Kilmer at the helm the first six games, the Redskins scored 83 points and were 3-3. Under Theismann, they have scored 70 points and won four of the six. Still, the Redskins have produced only seven touch-downs in those six games, and time and time again have had to depend on their defense to save them.

Allen also knows Kilmer produced more yards and points against the Cardinals in the first game between the teams than the Redskins have gotten in any other game this season.

Kilmer threw three touchdown passes in the 24-14 victory at RFK Stadium Oct. 2, and over three seasons has quarterbacked the Redskins to four victories in the last five meetings with the Cardinals.

In the October game, Kilmer completed 12 of 21 passes for 206 yards, was sacked only once and threw scoring passes of 12 yards to Frank Grant of 27 to Jan Fugett and of 53 of John Riggins.

The Redskins gained 610 yards that day, by far their best output of the season, running for 163 yards, another season high. Of course, they also had a healthy Riggins that day. He now is out for the season with a knee injury, replaced by rookie Clarence Harmon.

Kilmer, the man Allen reluctantly benched six weeks ago, took a severe pounding at the start of the season. He was sacked 18 times, and had a sore knee, bruised shoulder and an aching back as a result.

Redskin sources said Kilmer has recovered as well as could be expected and that he is now as healthy as a 38-year-old quarterback can be. And the Cardinals' defensive line, which has only 24 sacks this season, is not considered a fearsome foursome.

Allen also may have another surprise in store for St. Louis, because linebacker Chris Hanburger is working with the first-team defense after spending most of the season either recovering from an appendectomy or a knee problem.

Hanburger went the distance in the first game against the Cardinals, his only complete game this season. Asked if he would start Hanburger in St. Louis, Allen said. "I would think not, but we might use him in passing situations."

Allen said he is scrambling just to get enough bodies for practice, that "this is the lowest we've ever been with personnel . . . I don't even know who I'm going to take off the active roster for the two-man cab squad Satruday."

"It's a predicament," Allen said, his voice reaching fever pitch. "I had another defensive lineman in (for a tryout) today in case we have to bolster that position. Dallas Hickman has a big cast on his hand, and he can't play on defense with that.

"We're really hurting. But I'll do what my judgement dietates, what's always been correct and will help us to win."