After stealing Bobby Carpenter in the NHL draft this summer, the washington Capitals owed the Hartford Whalers a favor. They obliged tonight, bringing only eight regulars here for a game that resulted in Hartford's first victory in six exhibitions, 5-3.

The Whalers had to suffer a bit just watching Carpenter play, however. The 18-year-old scored a goal and twice raced back on defense to break up good scoring opportunities in the third period.

"He's a smart hockey player," said Larry Pleau, Hartford's general manager and coach, who was outmaneuvered by Washington's Max McNab on draft day. "He has a good head on his shoulders and he knows the game. The kid's got a hell of a way about him. He's mature for his age. He'll be a good one."

Hartford, aided by Don Nachbaur's penalty shot, built a 4-1 lead while the Capitals were becoming acquainted in the first 40 minutes. But Washington made it close in the final period until the Whalers' Ray Neufeld scored with 5:34 to play.

Chris Valentine, standing just outside the crease, took Jim McTaggart's long pass and beat goalie Greg Millen at 2:06 of the third period to reduce the deficit to 4-2.

Then Neufeld slashed McTaggart, drawing the first penalty since the opening period. A makeshift Washington power play capitalized when Carpenter kept the Whalers from clearing their zone, whirled and sent a 50-footer that Millen muffed. It was Carpenter's fifth goal in seven exhibitions.

Hartford struggled to regain its composure. It began pressing the Washington defense, weakened in the second period by the loss of Rick Green with an aggravated left groin pull.

Twice, Blaine Stoughton was open in front of the Washington net, first on a superb pass from Nachbaur and later on a two-on-one break with Rick MacLeish. Each time, Carpenter came swiftly from behind to knock the puck away.

Finally, Neufeld's shot from close range struck the arm of goalie Rollie Boutin and dropped just over the goal line. Boutin later stopped breakaways by Jordy Douglas and Rick Meagher in making a strong bid for the backup goaltender spot.

Mike Palmateer, the No. 1 man, made his first appearance since returning from Europe and wandered a bit during two periods, in which he allowed four goals on 16 shots. Coach Gary Green, who wants Palmateer to stay more in the net, excused this performance on the basis of the less-than-stellar defensive effort in front of Palmateer.

Nachbaur's penalty shot came with Hartford shorthanded. He stole the puck from Bengt Gustafsson and started in on a breakaway, only to be hooked down by Dwayne Lowder-milk. Referee Ron Hoggarth immediately signaled the penalty shot and Nachbaur, after faking Palmateer, backhanded the puck behind the goalie.

Gustafsson scored Washington's first goal on a 40-footer off Millen's pads, but lost the puck on numerous occasions, one of which was converted into a breakaway score by Mike Rogers that gave Hartford a 4-1 lead.

"I counted one guy who might not start the season for them and 11 who probably won't play for us, so I'm not unhappy," said Gary Green, who promised a full squad of regulars for the 7:30 exhibition against the Philadelphia Flyers Friday night in Hershey, Pa.