The Washington Capitals last night started March in the same fashion as they did January, with a shutout of the New York Rangers.

Goaltender Al Jensen blocked 20 shots and Jorgen Pettersson scored two goals 29 seconds apart, including the game-winner, as the Capitals ground out a solid 4-0 victory before a Capital Centre sellout of 18,130.

Coincidentally, Jensen was in goal and Pettersson scored the winner on New Year's Day. Since that 3-0 victory, Washington had not shut out anybody and Pettersson had only two goals, neither a game-decider.

Last night's victory lifted the Capitals within five points of Patrick Division leader Philadelphia. The Rangers fell five points behind Pittsburgh in the battle for fourth place and the last playoff berth.

But more important to the Capitals' outlook was their second straight outstanding defensive effort.

Rod Langway scored his first goal of the season, then said: "I don't care about the goal. The thing I like is that we got a shutout and right now we're getting good defensive play from everyone.

"We're getting good skating from our wingers, we're using our speed to make their defensemen stay wide and we're getting more room down the middle."

There was plenty of shooting room last night, with the Capitals firing 32 shots at Glen Hanlon and missing the net on innumerable others. As usual, though, they had a lot of trouble finishing off the opportunities.

Pettersson produced the only goal Jensen needed on the Capitals' ninth shot at 13:26 of the first period. He crossed the blueline and fired a 45-footer that struck Hanlon on the right arm, popped off the crossbar and dropped into the net.

"It was really high, and if he hadn't hit it, I think it would have gone over the net," Pettersson said. "It hit the crossbar anyway, so I guess I was pretty lucky."

There was no luck involved when he scored again on the same shift, taking Mike Gartner's pass and hitting the far corner from well out on the left wing.

"I saw Howie Alan Haworth going in on the right side and I was thinking to pass to him, but the defenseman favored him and when he did, I got a shot away," Pettersson said.

Pettersson came close to a hat trick in the second period when he tipped Haworth's pass between Hanlon's legs, but the puck struck a post and skipped away. On another occasion, Pettersson lifted the puck from Tom Laidlaw and was tripped, giving Washington a power play.

"He Pettersson shot the puck very well and he had a couple of quality plays besides that," said Coach Bryan Murray. "He's done more with the puck lately than he had earlier. I like that line Pettersson, Haworth and Gartner . If they play up to that level in the playoffs, we'll be in good shape."

Pettersson has five goals in four games against the Rangers this season, one coming with Hartford before he was traded here for Doug Jarvis Dec. 6. Over his career, he has 14 goals against the Rangers in 19 games and he scored his first NHL goal in his first shift at Madison Square Garden in 1980.

"I have scored a lot of goals against them, but I can't explain why," Pettersson said. "This was only one game, but that's what I have to do and maybe this will take the pressure off me a little.

"The last few games I've been feeling pretty good and getting some chances. I haven't been playing close to what I can do. Maybe it's tough to come to a new team, because they don't know me and I don't know them. I'm not big in the corner, I play best from the slot. Shooting, handling the puck and skating are my game. If I do that, I can help this team."

The Rangers, who had won seven of their previous eight games, tried to mount a comeback early in the second period, but Raimo Helminen somehow missed an open net on a setup by Brian MacLellan and thereafter Washington was in control.

Langway picked off a clearing attempt and hit from the left point early in the third period and Bob Gould finished the scoring when a shot by Bob Carpenter struck him in the hip and deflected past Hanlon.

Jensen made big saves on Kelly Miller and MacLellan with the game scoreless, then stood back and appreciated the work of his teammates.

"The guys played great for me," Jensen said. "They played a great defensive hockey game. It was nice to get a couple of tough shots early and get into the game right away, because I hadn't played in a week. But after that, they made it easy for me."

Jensen will be back in the net tonight, when the Capitals and Rangers meet again at Madison Square Garden, and he said: "I feel good. I'm not tired or anything. All I'm worried about is the win."