Coach Dick Motta won't have to give a Knute Rockne lecture today before the Bullets meet San Antonio. His players don't have to be told that the game is the most important of the season.

If the Bullets can win the 1:30 p.m. contest in Capital Centre, they will hold a 3-1 lead in games and will be in commanding position to capture this best-of-seven NBA playoff series with the Spurs.

If Washington loses, the Spurs will regain the crucial home-court advantage when the series returns to San Antonio Tuesday.

A crowd of at least 15,000 is expected by Bullet official, who announced yesterday that tickers in all prices ranges are available. Since the Centre was not sold out in advance, the game will not be shown on local television by CBS. It can be heard on WTOP radio.

"We need to be up three games to one," said Motta. "It doesn't take a mathematical genius to figure that out. Then we only need to win one of the last three games. Those are the odds I like to work with."

Motta is hoping that fear will motivate the Bullets: fear that they lose the fourth game like they did in last year's Houston series and fear that the Spurs suddenly will start playing like the team which compiled the NBA's third-best record this season.

"We should be afraid of them," Motta said. "By now we should know how good they are. One letup and they can beat us."

Whether it's been the Bullet's superior all around or their own lack of organization, the Spurs have not performed well since winning the opening game last Sunday in San Antonio.

They were a 50 percent shooting team during the regular season, the best in the league, but they haven't shot better than 43 percent in losing the last two contests. And they've wound up relying on George Gervin and Larry Kenon to supply the bulk of their offense.

But Bullet center West Unseld, who is going through his 10th year of playoffs, is trying to warn his teammates that "anything that's happened so far in this series means nothing.

That has to be good news for Spur Coach Dough Moe, who is searching for some ray of hope amid the dark could that was surrounded his club. Everyhing that got the Spurs into the defense, their teamwork and their fast break - has collapsed and he isn't certain why it's happened.

We've got to get more playing out of just about everyone on the team except Gervin, Kenon and (Mike) Green," said Moe. "They need help."

Starters Coby Dietrick, Bill Paultz and Mike Gale combined for only nine points in the Bullet's 118-105 victory Friday night. The three totaled 18 points when Washington won Tuesday in San Antonio.

Paultz, the bulky 6-foot-10 center who averaged almost 16 points and nine rebounds in the regular season, has been plagued by a sore back. He has contributed subpar totals of 17 points and 13 rebounds in the two losses. Gale, the playmaking guard who has bothered the Bullets all season, scored five points and handed out eight assists in the same games.

Moe said he was contemplating chnages in his starting lineup, but hadn't decided on them yesterday. Good possibilities would be Mark Olberding for Dietrick and Louise Dampier for Gale. Green could replace Paultz at center, but that seems less likely.

"We've also got to get into our passing game better," said Moe. "We get behind and we get impatient to catch up."

The Bullets were just as impatient in the opening game of the series, when they stopped running their offense in the second half and lost by 11 points. Since then, Motta couldn't ask them to play much smarter.

"We are playing intelligent basketball," said Bob Dandridge, who has stablized the Bullet offense since returning from a neck injury. "The young kids on our team are enthusiastic and it's rubbing off on the veterans.

"We are privileged just to get this far in the playoffs, considering our injury problems. We are as healthy as we've been in a long time and it shows. It seems like we want to make sure we don't blow the opportunity."

The players have done a fine job of listening to Motta's pleadings about executing fundamental basketball against San Antonio and not get involved in a free-lance, undisciplined game, which is where the Spurs function best.

"You can beat this team by running basketball plays," is how Motta puts it, meaning as long as his club performs what is written in the playbook and doesn't adlib, it can be successful.

This is true even when the Bullets run. In the opening contest, their running game was a helter-skelter affair that created more turnovers than baskets and allowed the Spurs to quicken the tempo to a level they desire.

Now Washington's fast break is almost picture perfect. Tom Henderson or Larry Wright is acting as the middle man with Dandridge, Elvin Hayes and Kevin Grevey filling the lanes on either side, just as it's diagrammed on the dressing romm blackboard. And when the break isn't there, the playmakers are pulling up and setting up the offense, which is producing a series of easy layups against San Antonio's gambling defense.

The result is better-than-normal shooting by the Bullets. They've made 55 percent of their attempts the last two games, compared to a 46 percent mark for the regular season.

"It's because we are doing the little things," said Unseld, who had criticized the club for poor execution a few weeks ago. "Like when Elvin is being double-teamed, he is looking outside and making that pass to the open guard.

Or when we are coming down on the break, we are hitting the man on the weak side for an easy jumper. We are moving the ball around, and helping out. That's what wins games and that is what we have to keep doing."

Washington is now 15-0 this season before home crowds of at least 12,000 . . . The Bullets also have won 33 of 38 games in which they have shot a better percentage than their opponents . . . When Washington outrebounded San Antonio by 10 in the opening game, much was made of the Bullets' inside muscle. But in the last two contest, San Antonio has won the rebounding battle and lost both times . . . Hayes has made 37 of his 61 field-goal attempts against the Spurs, including a bunch of those bad angle turn-around jumpers that leave defenders shaking their heads.