There was enough bad-mouthing between Ivan Lendl and Eddi Dibbs last night to make Sugar Ray Leonard Versus Thomas Hearns Look like a sibling rivalry. But top-seeded Lendl backed up his talk with crushing forehands and eliminated the 10th-seeded Dibbs, 3-6, 6-1, 6-1, at the Rock Creek Tennis Stadium to advance to today's quarterfinal round of the Washington Star International.

Also advancing were third-seeded Jose-Luis Clerc, fourth-seeded Guillermo Vilas, 12th-seeded Mel Purcell and unseeded Andres Gomez, Raul Ramirez, Mario Martinez and Stanislav Birner, a qualifier.

The biggest surprise among the quarter-finalists is Ramirez, who has done relatively little the past three years. But he defeated Uruguay's Diego Perez, 6-3, 4-6, 6-2.

In the evening's final match, Clerc eliminated Spain's Angel Giminez, 6-3, 6-1. Clerc was a finalist last year and will face Ramirez tonight on the stadium court.

But the match everyone awaited all day was Lendl versus Dibbs.

Dibbs was on an emotional high in the first set, forcing the action and using drop shots and lobs effectively as Lendl fell behind for the first time in this tournament.

Early in the first set, the players began glaring, then taunting and pointing fingers at each other.

"He said something that got me hacked off at the first changeover of the game," DIBBS SAID. i don't particularly like the guy anyway, so I went back at him."

A fired-up Dibbs broke serve to take a 3-2 lead, then held his serve. After a long deuce game, in which Dibbs held serv e again for a 5-3 lead, Dibbs pointed toward Lendl and began shouting. Every time Dibbs hit a winner he would walk to the service line and glare at the Czech as the stadium court erupted in cheers for Dibbs.

At the end of the first set, Dibbs spent nearly the entire rest period jawing at Lendl, who was also talking and gesturing.

"What was being said is between me and Dibbs," Lendl said. "I've beaten him all five times we've played."

Dibbs put so much into winning the first set that he appeared to tire.

When Dibbs lost his edge, Lendl took over. Lendl, ranked fourth in the world, won the first four games of the second set with an astounding array of winners lauched from his forehand, which many consider among the best in the game.

"He starts whaling the ball off the racket. I don't know where it's going," Dibbs said. "And I'm not sure he does either. He's flashy on the forehand but he misses a lot. There are a couple of guys around with better forehands."

Still, Dibbs couldn't survive Lendl's base line strokes or volleys and managed to win only two games in the last two sets. "I'm playing off and on," Dibbs explained. "Just inconsistent."

On the other hand, Lendl said he is feeling "as good as I can feel." Lendl's next opponent, Ecuador's Andres ygomez, is a rangy (6-foot-5), unpredictable player who isn't expected to wear down as quickly as Dibbs.

During the rain-delayed afternoon action, Vilas, three-time Star champion, moved into the final eight, by defeatng California's Erik van Dillen, 6-1, 6-3. Vilas has yet to be tested.

Either Vilas is returning to his mid-1970s form or his opponents are sub par. Since he faces unseeded Mario Martinez in his quarterfinal match, Vilas probably won't know which until the semifinal.

Martinez advanced by defeating Pascal Portes of France, 6-4, 6-3.

Gomez upset 11th-seeded Jose Higueras of Spain, 6-4, 6-3.

Birner outlasted Terry Moor, 6-4, 2-6, 7-6, in the only match completed before a two-hour rain delay. Birner had barely made it the field of 6-4.

He had to defeat Rodney Harmon in a tie breaker in the final qualifying round to get into the main draw. Birner, who was overlooked by his Davis Cup captain two weeks ago when Czechoslovakia lost to the United States, joins countryman Lendl in the quarters.

Birner will face his third seeded player, No. 12 Mel Purcell.

Purcell, the unquestioned crowd favorite, won his second come-from-behind match, 2-6, 6-4, 6-3, over seventh-seeded Eliot Teltscher.