In prizefighting, the boxers never bother to say nice things about each other because they know they are going to have a fight, anyway. In baseball, however, gentlemanly discourse and a diplomatic stroking of the opponent's feathers before a crucial meeting has generally been considered wise.

For the New York Yankees and Kansas City Royals, that rule does not hold. They already dislike each other intensely. Today, the Yanks, particularly Ron Guidry, who will start Wednesday afternoon's first game of the American League playoffs here (3 p.m. EDT, WJLA-TV-7) against Larry Gura, added another log to the fire with an uncharacteristic salvo of borderline braggadocio.

"It takes a whole helluva lot of luck for them to beat us," said Guidry, "because we always seem to get the breaks. But you don't know if we make 'em (the breaks) or if they give 'em up.

"They have to prove they can beat us. We don't have to prove anything. Sure, it has to work against them that we've beaten them three times in the playoffs ('76, '77, '78)," said Guidry, who has won his last four decisions, and whipped the Royals with complete-game victories in the '77 and '78 playoffs. "Anything can happen. They could sweep us, or we could sweep them. But if they did beat us, what would it prove? It would prove they could beat us one year. The only thing that would do would be to help them next year if we meet again.

Asked if he thought the second-best team in the American League was Baltimore, whom the Yanks have already dispatched, Guidry said, "Well, the Western Division is not as strong as the East. You can't convince me otherwise."

Unless you knew better, you might think the Yankees were ruffled at the way the Royals have beaten them in eight of 12 meetings this year, out-scoring New York, 89-56. The Yankee team ERA against the Royals for '80 is 6.73, while the K.C. batting average is .336, led by George Brett who slugged .900 and drove in 22 runs against the Yanks in only 10 games. Although the Royals aren't broadcasting it, they think they have the Yankees' number and may thump them badly.

The Royal book on the Yankees is that you can wear out their starting pitchers and thus keep Goose Gossage out of the game, that you can run on their awful defensive outfield (especially on Astro Turf) and that you can steal on catcher Rick Cerone, even with the Yankees starting this series with three straight lefties -- Guidry, Rudy May and Tommy John.

The proud New Yorkers don't even appreciate people thinking such things about them. "Every time we met this year," said Guidry, "they had their top pitchers going and we never had our top line ready -- until this time.

"The way to beat them is to keep those speed demons (Willie Wilson and U.L. Washington) off base before George Brett comes up," said Guidry. "I understand you're not allowed to come out of the dugout and steal second.

"If you keep the bases empty, Brett can hit his homer and it's only 1-0. But if he comes up with two men on and hits a gapper, you're looking at 3-0. That's how they win. You better not count on stopping Brett to win. If you shot the ball out of a cannon, he'd hit it. In fact, if you threw no pitch at all, he'd still get a hit -- or they'd give him one."

So, was Guidry certain that the Yankees would win?

"Everybody wants the wine and roses," said Guidry, "but sometimes you get slipped some sour pork."

For the past two years, Guidry has "struggled" to 18-8 and 17-10 records after his 25-3 mark in '78. Each year, he's voluntarily exiled himself to the bullpen to get straightened out. Now, it appears, he believes he is ready to step back on center stage and get some respect. When, for instance, did Guidry feel that he would get the prestigious No. 1 playoff start over ERA champ May and 22-game winner John? "When I went back in the rotation (in September), I knew I'd be the one," he said.

If this sounds extremely unlike the mild-mannered Guidry style, that's right. The Yanks today sounded as though Reggie Jackson had mimeographed their public statements. Are they worried, or just totally confident? Or is it a tactic to make the Royals forget their 33-runs-in-12-games superiority this year and think back to uglier times?

"I know that I'm intimidating," said Yankee reliever Goose Gossage this afternoon. "I've always been that way, ever since the minors. Once, I threw a curve ball into the other team's dugout . . . tried to break it off real good . . . their coach put a batting helmet on in the dugout . . . Davenport against Appleton; so, I know how other players feel about me. When I'm in a groove, I can throw 100 mph on the black (corner of the plate). I might not know what I'm doing off the field, but on it, I think I'm the best. Rich Cerone thinks he's the best. Buck (Jackson) thinks he's the best.

"Everybody in this room is the best," said Gossage, the reliever Yankee pitching Coach Stan Williams describes with one word -- "prehistoric."

While the Yankees, winners of 103 games, are comfortable with bombast, the Royals seem to enjoy the role of underdogs (7 to 5) laying a trap. "Throughout September, I was worried about our level of intensity," said Manager Jim Frey, who, along with the Yanks' Dick Howser, are the first pair of rookie managers ever to meet in the postseason. "I called team meetings and told 'em how tough it was for me to give pep talks or chew people out when we were 18 or 20 games in front. But I warned 'em that it's awful tough to turn it back on the day you need to if you've been playing sloppily.

"But, in the last week, we've geared it back up; won five of our last six. I think we're right back where we want to be," said Frey, who is confident enough that he has benched Clint Hurdle, who hit .478 against the Yanks this year. In fact, the Royals won their last two games with a 17-1 triumph on Saturday and a one-hitter on Sunday.

"We've all had enough time to prepare the way we want to," said star Reliever Dan Quisenberry, who, along with .326-hitting, 79-st phenomenon Wilson, is the heart of the new improved version of the Royals that the Yanks haven't beaten in a playoff yet. "For instance, I've thrown the last two days so I can get good and weak," said Quisenberry, whose submarine sinker is better when he is tired and underpowering. "When your strength is weakness, you have to find a way to get good and weak. I'm looking for some new king of bacteria . . . maybe a strain of Agent Orange.

"When I'm too strong, my sinker doesn't sink, like the one Reggie (Jackson) hit off me here this year; it was a liner that never sank. It embedded itself in the embankment beyond the center field fence and it's now burrowing its way to St. Louis."

Like all the sly Frey-taught Royals, Quisenberry does not mention that that one Jackson solo homer was the only run the Yanks got off him in 12 innings this year (0.75 ERA). By contrast, Gossage's '80 ERA against K.C. was 6.35, Guidry's 6.48, and John's 16.20. Those stats, of course, are deceptive. All three of those key Yanks have great career numbers against the Royals.

The quiet pitcher today, and the one that the vital first game may depend on, is high-strung Larry Gura. He started this year 18-5, then went 0-5 in his last eight starts as his 283 innings were 50 more than he had ever pitched. In addition, he is 1-2 with a 5.21 ERA in five playoff games against the Yanks.

Gura, the man Billy Martin ruthlessly loved to call "gutless," has a 7-1 career regular-season record against the Yanks, 3-0 in '80, but he has to prove he has the stamina and nerves to win in the playoffs. If this affair goes five games, he would pitch the last contest after the Royal progression of 20-game winner Dennis Leonard, Paul Splittorff and Rich Gale.

As always, the scenario here -- whether it truly reflects reality or not -- is the proud, wealthy Yankees against the hard-nosed, homebody Royals. Perhaps Quisenberry gave just the proper final aw-shucks note to this day of preplayoff workouts. Quiz, who was in AA ball just two years ago, faces the prospect of having his salary go from $40,000 in '80 to a Yankee-like $400,000 in just one year.

"When I got married in '79, I thought I'd be happy just getting a regular job in the Post Office, or finishing my degree and teaching for $15,000 a year," he said, grinning. "Now, I'm almost forced to think about things I never thought I'd have. But I've decided that I absolutely will not get a palace. I will not get a moat. I can't afford the alligators. I don't like drawbridges. And there's always that wasted dungeon."

Of course, he could use the dungeon as a guest room -- for the Yankees.