Each summer since 1982, Magic Johnson of the Los Angeles Lakers and Isiah Thomas of the Detroit Pistons have carried their friendship onto basketball courts throughout the country. The "all-star games" they play in are really little more than an opportunity for the two guards to exchange behind-the-back passes, unbelievable shots and lots of giggles. After all, how serious can the games be when their final scores are often something like 179-176?

By the time next summer rolls around, however, those games may have turned into grudge matches -- extensions of their teams' heated battle for the NBA championship in June.

To meet in the NBA finals, however, the Lakers and Pistons have sizable obstacles to overcome. Besides the Houston Rockets, Utah Jazz and such rising powers as the Seattle SuperSonics and Golden State Warriors, Los Angeles must overcome the stigma of being the defending champion. For the past 17 seasons, no team has been able to repeat as titlist.

After winning the 1986-87 championship over Boston, Lakers Coach Pat Riley "guaranteed" his team would repeat this season. The reason? Instead of approaching the championship as a one-time achievement, Riley said he convinced his players they were on a two-part quest. Thus, the team's triumph in June (its fourth title of the decade) was merely half the goal.

Apparently, the team's fans have been similarly convinced. In a diffuse metropolis with endless alternatives for the entertainment dollar, the Lakers have sold enough season tickets to virtually sell out each of their 41 regular-season games at the 17,505-seat Forum.

Fans have always flocked to the Pontiac (Mich.) Silverdome, but now the entire league is watching to see if the Pistons' 1986-87 effort -- a berth in the Eastern Conference finals and a seven-game series loss to Boston -- was a fluke.

This is expected to be the season the Celtics' reign of four consecutive conference championships comes to an end, and Detroit or Atlanta is expected to be the successor. The Hawks won the Central Division title over Detroit last season and may have the most athletic team in the NBA, but even some in Atlanta believe the Pistons are ready to overtake them.

"Isiah Thomas, Adrian Dantley and Bill Laimbeer are so much smarter at their positions than our guys are," said a Hawks official recently, referring to guard Glenn Rivers, forward Dominique Wilkins and center Tree Rollins.

But while the Hawks have shown a tendency to self-destruct in the postseason -- suffering less-than-competitive losses to Boston and Detroit the past two years -- the Pistons must rebound from last season's playoff loss to the Celtics. The fifth game of that series stands out, when, trying to protect a one-point lead with three seconds to play, the Pistons suffered brainlock.

With the ball deep in their back court, players such as Rodman ran ahead, waving their arms as if the game was over. Thomas threw a lollipop pass to Laimbeer that was intercepted by Larry Bird, who passed to Dennis Johnson for a game-winning layup. The entire sequence would never have happened if Thomas or Coach Chuck Daly had called time to move the ball to midcourt.

In the NBA, a team's chemistry is perhaps the most important intangible. And entering last season, it was thought Thomas and Dantley would be unable to play together. That was proven false, albeit after a slow start.

This season, there are more questions as Dantley goes to work with a brand-new contract extension, hoping to improve over last season's 21.5 points a game -- 4.5 under his career average. There also is the fact that Thomas isn't the most popular person with his teammates.

But, regardless, look for the Pistons to hang tough.