A week ago, the Washington Capitals were stumbling along with a five-game winless streak and it seemed about time to write another chapter in that unending book called "What's Wrong With the Capitals?"

Then, on successive nights Washington defeated two of the top three teams in the National Hockey League, Philadelphia and Chicago. Apparently, a cure had been found for that two-week case of the doldrums.

On Friday night, however, the Capitals yielded eight breakaways and were beaten, 5-4, at Capital Centre by a struggling Quebec team whose defense was riddled by injuries.

Afterward, Quebec Coach Michel Bergeron suggested that the Capitals had been "overconfident."

Washington Coach Bryan Murray used a few other words and from his expression and the perspiration on his forehead, it was obvious he was distraught by his team's latest failure in front of 13,365 home folks.

"I really thought that after winning over two of the top teams in the league all this stuff was over with," Murray said.

"But with a young hockey club I guess it's never over. They should never get three-on-twos or two-on-ones like that.

"It was like a teeter-totter thing. One guy stays and the other one doesn't and it all breaks down. It's easy to show on the blackboard, but apparently some of our players just don't understand.

"To lose at home to Los Angeles and Quebec, the same caliber teams, it's so frustrating."

In 1983, the Capitals are 3-1-1 on the road, 1-5 at home. The Capital Centre victory was over Philadelphia, which had won eight straight on the road and is the hottest team in the NHL.

The losses were to the New York Rangers, whose only other road success since November came at New Jersey; Toronto, for the Maple Leafs' only win away from home in a full year; Los Angeles, otherwise winless on enemy rinks since November; Buffalo, for the Sabres' only road victory of 1983, and Quebec, which had last prevailed on the road at Pittsburgh six weeks ago.

Tonight, New Jersey visits Capital Centre for a 7 o'clock game and with the Devils' poor record the Capitals would appear ripe for an easy victory--and another case of overconfidence.

"I'll have no problem finding fire to get them up for this one," Murray promised. "I'm so mad."