A week ago, the Washington Diplomats were celebrating an intoxicating victory over the Cosmos before 27,000 at RFK Stadium.

Yesterday, in their first home game since that memorable night, the Diplomats gave away three sloppy goals and lost to the Tulsa Roughnecks, 3-2, in overtime. And only 8,484 fans showed up at RFK Stadium on a lovely, breezy afternoon.

When it was over, Diplomat Coach Ken Furphy was screaming at the North American Soccer League supervisor of officials, Keith Walker, about the performance of referee Gino D'Ippolito. Furphy felt that D'Ippolito ignored three penalties on Tulsa, including one in the second overtime.

"I've said all along that sooner or later we're going to lose because of a bad call by the referee or because of silly goals being given up at the back," Furphy said. "Today, both of those things happened.

"It makes me sick that my team has to play games refereed by that man. I hate him out there.He loves the power. I don't mind losing 4-0 if I get overwhelmed. I do mind losing like that. He's an arrogant . . ."

"He didn't give away the silly goals," Walker replied.

The Diplomats (8-4, 63 points; 20 points behind the Cosmos) fell behind, 2-0, before it dawned on them that merely showing up did not guarantee victory over the team they beat Monday night in Tulsa, via shootout. Then they stood around in the last minute of overtime waiting for a shootout that never came.

"I thought for sure we had made all the mistakes we were going to make and we would go into shootout," said midfielder David Bradford. "They won because they were hungrier for it than we were."

The Diplomats' final mistake came moments after goalkeeper Jim Brown had wiped out a mistake by making a leaping save on Duncan McKenzie's high chip shot from 15 yards.

Brown cleared the ball, but Alan Woodward, only a part-time player now at 35, recovered it for Tulsa. He passed right back to McKenzie, who had his back to the goal and defender Peter Carr, his shadow all day. McKenzie faked Carr left, turned to his right and fired a low shot from seven yards out that skipped through the surprised Brown's legs into the net, ending the long afternoon at the 104:05 mark of the game.

"I thought I'd won the game on the chip shot but Brown made an unbelievable save," McKenzie said. "I was still standing there cursing the luck when Woodward played the ball back to me. I just made one quick face, turned and shot."

"He got me turned the wrong way," Carr said. "We'd had our chances to finish the game before that and didn't do it. It's one battle, though, not the war."

For the first time this season, Carr and his comrades on defense gave away cheap goals. They spotted Tulsa (6-5, 49 points) its 2-0 lead in the first 17 minutes on what Furphy called "two casual goals created by two bad mistakes."

The first came at 4:48. Malcolm Waldron tried to send a soft pass back to Brown, who was not expecting any kind of pass. By the time he started toward the ball, Dean Neal had beaten him to it. Neal lofted the ball past Brown to Billy Caskey, who scored easily into the open net.

The second goal, at 17:20, was at least partly created by McKenzie's hustle. Iraj Danaifard sent a long pass down the left side and McKenzie beat Carr to it just before it crossed the end line. He stopped short and flipped a pass back to Neal, who flashed across the box and beat Brown to his left from 12 yards.

"We were overconfident at the start, no question," Brown said. "It took falling behind 2-0 to shock us into playing. We were lucky to get back in it."

Two goals by 6-foot-6 Ross Jenkins, the elongated man of soccer, brought the Dips even.

In the 37th minute, Heinz Wirtz lofted a free kick into the box over the head of Tulsa goalie Zeljko Bilecki. The ball caromed off defender Paul Hunter to Jenkins, who scored standing almost on the goal line to make it 2-1 at 36:41.

It looked as if it would stay 2-1, and did until the final six minutes. Brown flipped a long pass to Jenkins, who passed to Willi Kiefer. The two worked a lovely give-and-go and Jenkins finished the play by blasting a 15-yard, left-footed kick past Bilecki, his fifth goal of the season, at 84:11.

That set up the overtime. In the 100th minute, Washington's Trevor Hebberd dashed into the box and was taken down from behind by Hunter. D'Ippolito ruled "play on" and the Washington bench was outraged at the no-call.

"Clearly a penalty, clearly," Hebberd said. "Everyone in the stadium saw it except the referee."

"He hasn't made a good call in five years," Furphy said.

"Had to be a penalty," Washington General Manager Duncan Hill said.

"Just a bump," Hunter said.

"Certainly suspicious," Walker conceded.

Four minutes later McKenzie, an outstanding English League player for 10 years (170 goals in 390 games) who said he spent the entire bus trip this morning gaping at the sights, put an end to Washington's unbeaten record at home.

"Disappointing day," Hill said. "I had hoped more people would have come back today instead of waiting for the next Cosmos game. Then, we didn't play very well and lost."