The Rochester Lancers extended their home-field victory streak to 13 tonight by using an aggressive, mugging defense to shackle the Washington Diplomats, 2-1, in a North American Soccer League game before 4,942 at Holleder field.

Washington was riding high, haveing won four straight coming into to completely choked off the Diplomats. The only time the hustling Rochester squad relaxed Peter Silvester knocked in a goal with 6:20 left to prevent the outplayed Dips from being shut out.

Washington coach Dennis Viollet and several of the players were very upset with the officiating. A total of 58 fouls (30 against Washington) were called and five yellow cards (caution warnings) were handed out by referee Tony Nobile.

"it was terrible out there," said mid-fielder and assistant coach Alan Spavin. "They were taking our legs right out from under us. I don't think any team could have got anything going against them tonight."

Viollet became so incensed following a vicious collision that sent mid-fielder Tony Macken crashing to the ground he rushed out on the field to confront Nobile.

"I told him it was disgraceful the way he was letting them play. That guy could have broken Tony's leg in three places," said Viollet.

"Playing hard and playing the ball is one thing, but they were coming over the top at us, going for the legs."

In spite of the foul claims, it would take some time to look back and find a game in which Washington played worse. Injured starting forwards Jim Redfern and Alan Green didn't make the trip and it showed on offense. The Diplomats had virtually no opportunities to score, were totally disorganized and were called offside five times.

The Lancers, extremely adept at the short pasing game, were content to sit back and wait for Washington to make a mistake.

They got their first break when Dip defender Ken Hill was called for a hand ball in the penalty area. Art Jorge easily boomed the ball past Washington goalkeeper Eric Martin at the 24:59 mark and Rochester led, 1-0.

Following a breakaway, Rochester's Ibraim Silva converted a rebound off Martin into Rochester's second goal. Craig Reynolds banged a 20-foot bullet that Martin managed to deflect but Silva was there to push the Lancers ahead, 2-0.

The Lancers lost three men on injuries. Jorge being the most serious with a fractured ankle.

Washington, now 5-4 with 42 points, lost its opportunity to quit the Eastern Division cellar. Both the Cosmos, 5-5 and 48 points, lost today.

Washington hosts Fort Lauderdale Saturdays at RFK stadium at 8 p.m.