It always seems to come down to a game of match-ups in the National Basketball Association and unless the Philadelphia 76ers find someone to guard George Gervin, this already trying season will end quickly for them.

The Spurs lead their best-of-seven Eastern Conference semifinal series with the 76ers, 2-0, having won Sunday and Tuesday at HemisFair Arena.

The third game of the series will be played tonight at the Spectrum, the fourth game also in Philadelphia Sunday.

Normally the 76ers match up well with San Antonio, but with Philadelphia guard Doug Collins out with a broken foot, the Spurs have had the advantage. San Antonio is playing its normal game and the Sixers have had to make all the adjustments.

Without Collins, Philadelphia's top three guards, Henry Bibby, Maurice Cheeks and Eric Money, are all 6 foot 1 or smaller and no defensive match for the 6-7 Gervin, the NBA's leading scorer the past two seasons. He scored 31 points in the first game of the series, 29 in the second and has made 25 of 37 shots in the series.

The 6-1 Bibby started on Gervin in the first game and was at a total loss. Philadelphia Coach Billy Cunningham then decided to use his best defender, 6-9 Bobby Jones, on Gervin in the second game. That worked better, but Larry Kenon, the man Jones usually guards, went wild.

Kenon averaged only 13.8 points and shot 35 percent from the field against Jones in four regular-season meetings. In the playoff series, he is averaging 28.5 points and shooting 51 percent.

For tonight's game, Jones will go back on Kenon.

"The next two games will depend on the Jones-Kenon match-up," said Jack McMahon, a 76er assistant.

"He (Kenon) is moving the ball, rebounding, bringing the ball up on the break and shooting well. We have to put our best defensive player on him. We can't let Kenon continue to run wild or we're going to lose," he said.

Kenon said he is not all that concerned with who guards him. "I'm going to be ready and aggressive," he said. "I'm not taking the attitude that the series is all over."

With Jones going back on Kenon, Cunningham said he will put Cheeks, the 6-1 rookie, on Gervin "and just hope he doesn't score 60."

That leaves Caldwell Jones guarding Billy Paultz, Julius Erving on Allan Bristow and Bibby on James Silas.

In winning the first two games, the Spurs also have been able to contain Erving and Darryl Dawkins, the 76ers biggest scorers, by double-teaming them whenever they get into scoring position.

Erving shot 18 times in the first game and 16 in the second and has scored 47 points.

"We can't win with Erving only getting that many shots a game," McMahon said. "He has to get at least 25 shots."

The 76ers are not the only playoff team in trouble. The weary Los Angeles Lakers lost the first two games of their Western Conference semifinal series to the Seattle SuperSonics at the Kingdome.

Gus Williams is no George Gervin, but he could fool Laker Coach Jerry West. With point-a-minute man Fred Brown ineffective because of a broken hand, Williams has turned into the Sonics' scoring machine. He had a career-high 38 points in the 108-103 overtime victory Wednesday to give Seattle the 2-0 lead, and has scored 65 points in the two games.

The Lakers scored 10 straight points to take a 95-93 lead with 10 seconds left Wednesday. Seattle's Jack Sikma took a 15-footer with three seconds remaining and Kareem Abdul-Jabbar blocked it. Sikma chased the ball down near midcourt, however, and rifled a pass to Dennis Johnson on the baseline. Johnson made a bad-angle 18-footer at the buzzer to send the game into overtime. CAPTION: Picture, Larry Kenon