When the Los Angeles Dodgers take batting practice, the last four men in the cage are always the same: Steve Garvey, Dave Lopes, Bill Russell and Ron Cey.

"Let's go, you midget infield," crows Lopes, proudly.

For nine years, this infield, which has played together perhaps longer than any quartet in the history of major-league baseball, has been the heart and soul of a Dodger team that has been to four World Series during their era. The skills of these four are the Dodgers' trademark; their limits are the Dodgers' limits.

When the 78th World Series resumes here in Chavez Ravine at twilight Friday (8:30 p.m. EST, WJLA-TV-7 in Washington), it may be the last stand for the 1981 Dodgers, who trail the New York Yankees, two games to none.

It may also be the last stand of their careers for one of the best and most durable, as well as one of the most maligned and unusual, infields in baseball history.

Most eyes Friday will rightly be on the special rookie lefties pitching in Game 3: Fernando Valenzuela for L.A. and Dave Righetti for New York.

Also, gimpy Reggie Jackson may or may not take himself out of cellophane. With his Yankees leading the best-of-seven series, Mr. October may wait. What's the rush?

However, from the Dodger perspective, the key to this Series is the ability of their battered and aging infield to rise above its infirmities and finally win a World Series. It's a tall order for a short infield.

"Those guys are all playing on guts right now," said teammate Reggie Smith.

Third baseman Cey has come back two weeks earlier than doctors ordered after a broken wrist; he comes to the plate with a plastic cast on his arm.

Shortstop Russell is playing with a stress fracture in his foot and an ugly mangled finger on his throwing hand. Also, he has chronic problems on the bottoms of his feet because of the high-temperature artificial turf; he will require postseason surgery.

Second baseman Lopes, who, at 35, is two years older than the other three, is wearing out at the end of a distinguished career that has seen him steal 418 bases. He has so many recurrent, never-gonna-go-away injuries to his neck, back and hands that he won't comment on which hurt and which don't. After hitting .206 this year, it's likely that his starting job will go to Steve Sax next year, thus breaking up the long-running act.

Iron man Garvey, whose current streak of playing in 945 games is the fifth-longest in history, has all his injuries on the inside. The overachieving, fiercely proud son of the Dodgers' one-time bus driver, Garvey spent the first 33 years of his life turning himself into a sort of model fortress of a person -- Mr. Muscle-and-Charm Perfection. Now, after his wife Cyndy has left him and taken the children, Garvey's chiseled face shows more of the whimsy and puzzlement that most men share, but Garvey never before acknowledged. It's a tough way to become more likeable.

In the past, the Dodgers have gone as far in the postseason as their infield, which occupies four of the first five places in the batting order, could carry them. That's to say, L.A. could get to the Series in grand style, but, once there, the Angelenos stumbled.

In four seasons of NL playoffs in 1974, '77, '78 and '81, the Dodgers have a 15-7 record; the Cey-Russell-Lopes-Garvey infield has stunning combined stats in those games of 14 homers, 50 RBI, a .314 batting average and a .514 slugging percentage in 325 at bats.

However, in these four Series, in which the L.A. record is an awful 5-14, those four have been as disappointing as they have been stellar in the playoffs. To date, in 294 Series at bats, they have only seven homers, 26 RBI, a .248 batting average and a punchless slugging average of .364.

Perhaps this is not so much a case of succumbing to pressure as it is merely an accurate measurement of the athletic limits of four dedicated, but not spectacularly gifted men.

"None of those four guys has ever heard the word 'awesome' applied to them," said Manager Tom Lasorda, who had them all as baby bush leaguers, in Ogden, Spokane, Albuquerque or Caracas. "Nobody looks at them and says, 'What God-given talent!'

"They're four of the hardest-working overachievers I've ever seen. I remember them when Garvey was a third baseman and Lopes and Russell were both center fielders. In the minors I had a hand in making them all infielders.

"It took years and years for them to learn their craft. I can remember hitting grounders for half an hour every day to Russell in Caracas in the winter league before anybody else was in the ballpark. All of 'em took more ground balls then any other players I ever saw. They wore my rear end out."

The Dodgers are thought to be a Hollywood team, a bunch of prima donna glamor boys. But the infielders aren't. They remember where they came from and how hard it was to get where they are.

"I had Lopes when he made $600 a month in Albuquerque, Cey when he made $700 a month there. And I had Garvey and Russell in Ogden when they were making $500 and $400 a month," said Lasorda. "And now Russell makes so much money that his bank called him the other day and said, 'Mr. Russell, we can't honor this check you wrote because of insufficient funds. Ours, not yours.' "

If the Dodgers have a heart, and some maintain that they don't, it's that minor league connection between Lasorda and his infield, plus catcher Steve Yeager. They're Tommy's Boys and never forget it. They came up together, made the headlines together, and now the era is winding down.

"I watched 'em grow up," said Lasorda.

And now, he's watching them grow old, at least as players.

Scurrying around the infield always has been hard work for these offense-oriented guys, three of whom are 5-foot-9 or a hair shorter, with only Russell measuring, according to Lopes, "5-foot-10 1/2 if he stands up real tall."

Now, with their injuries and the attrition of about 1,500 big-league games per man, their decade-old defensive liabilities are more obvious and painful than ever. As much as anything, it is Garvey's marvelous scooping ability on throws in the dirt that keeps them functional.

This quartet, which Lasorda said "is never flashy, just clutch," has always wanted the same thing -- a world championship to make it bonafide in the same sense as the great Dodger teams that won world titles in the '50s and '60s.

"It's going to be awful disappointing if we never win one," said Lopes.