Winger Willi Kiefer's goal shortly before halftime broke a 1-1 tie and the Washington Diplomats halted a three-game slide with a 2-1 victory today that also ended the 15-game Comiskey Park winning streak of the Chicago Sting.

Kiefer, known as "The Beast," clebrated his first North American Soccer League goal by somersaulting forward, then backward.

"This puts the boys in a buoyant mood," said Coach Ken Furphy, who was just beginning to think of Wednesday's home game against the Eastern Division-leading Cosmos.

The Diplomats (9-6), who had tied at 27:48 on Malcolm Waldron's penalty kick, not only showed an improved offense but played ruthless defense to shut down Chicago's usually powerful attack.

Assistant Coach Eddie Colquhoun, making his first start this season, held the league's second-leading scorer, Karl-Heinz Granitza, without a shot except for free kicks. The 36-year-old Scot forced the German striker to play almost the entire game with his back to the Washington goal.

Just as impressive was Peter Carr's marking of flashy midfielder Arno Steffenhagen, whose header gave the Sting a 1-0 lead at 18:07. Steffenhagen was not a factor in the second half.

Carr suffered a four-stitch gash on the right side of his forehead shortly before halftime.

Carr also strained a knee and bruised his leg in the game, which saw 41 fouls, seven yellow cards and one red card called.

Carr said he was slugged in the face by Steffenhagen at 17:47 and said he is contemplating legal action against the midfielder for the attack.

"Steffenhagen is one of the best midfielders in the league," said Carr, generally acknowledged as the toughest Diplomat. "But he has a bad temper and it really showed today."

Benny Dargle, Washington's right back, had five spike marks on his leg, apparently from the shoe of Frantz Mathieu, who was ejected in the second half. Kiefer, Trevor Hebberd, Heinz Wirtz and Peter Baralic also were hurting from kicks, spike wounds and punches.

While Washington trainer John Lally stitched Carr's face at halftime, the man called "Biff" kept joking to keep his teammates' spirits high. "Will I still be able to play the piano?" Carr asked Lally, blood dripping from his nose.

In the second half, with Carr, Dargle and Colquhoun shadowing their men, Chicago (10-5) rarely got a good scoring chance. Ivan Milkovic's shot hit the near post and the ball slid through the goal mouth, but no teammate was in position for a rebound. Dip goalkeeper Jim Brown also made three excellent saves in the last 22 minutes.

"Carr just sat on Steffenhagen and Eddie sat on Granitza," Furphy said. "Eddie put Granitza in his pocket every time."

"He (Granitza) always steps backward just inside the penalty line and falls forward as if somebody's pushed him, to draw a foul," Colquhoun said. "I know he's going to do it but I fell for it twice. Fortunately, I recovered both times. I've played this game a few years, you know."

"We played disciplined, textbook defense," Carr said. "It was worth it."

But several of the Sting said the Diplomats played over their heads. And Pato Margetic, who played on the Detroit Express last year before the team moved to Washington, and who assisted on Chicago's gaol, said, "We didn't care about this game. It's not good to lose, but we play the best soccer in the league. We just played bad today."