In what qualifies as must-see regular season basketball in the NBA, there is no better matchup than the Celtics and Lakers.

Well, that’s one theory. The resurgence of the Celtics combined with the ongoing success of the Lakers once again rekindled this wonderful rivalry, which dates back to some searing competition in the 1960s. Larry Bird and Magic Johnson brought it back in the 1980s (while pretty much saving the NBA in the process) and now we have them once again among the league’s elite, accounting for the last two NBA titles.

But a little bit of the bloom is off the old rose as the two teams meet for the first time this season on Sunday afternoon in Boston before a national television audience. The Lakers are upholding their end of the deal, entering with a 36-11 record, best in the demanding Western Conference and second overall to Cleveland.

The Celtics? Well, let’s be charitable and just say they’re in a bit of a funk. They’ve dropped their last two games and have lost 10 of their last 16 to fall to No. 3 overall in the not-so demanding Eastern Conference. The Friday night loss to Atlanta could cost Celtics boss Doc Rivers a berth as the coach of the Eastern Conference All-Stars next month in Dallas. (That is not exactly high on Doc’s priority list right now.)

Not much has gone right for the Celtics since they thrashed the Magic on Christmas Day, improving to 23-5. Paul Pierce missed five games with a knee ailment and the team lost three of them. Kevin Garnett missed 10 games with a hyper-extended knee and the team struggled without him, losing six. Although he has returned, he bears little resemblance to the fiery and feisty KG who led the team to the NBA championship two seasons ago. He moved around like Billy Paultz in the Thursday night game in Orlando and was marginally better the next night in Atlanta.

Ray Allen and the words “expiring contract” are now being mentioned in the same sentence as the trade deadline nears, a heretical thought not too long ago. Allen, who scored only 9 points on Friday, is averaging 15.9 points a game, second fewest in his career. He’s also taking the fewest shots per game since he came to Boston, all the while leading the Celtics in total minutes played.

While Rajon Rondo has blossomed into an All-Star, and Pierce continues to play at a steady clip, the bench is a nightly challenge for Rivers. Rasheed Wallace has been up and down (but still leading the league in technical fouls) and sharpshooter Eddie House is in a slump. Rondo has no real backup and the Celtics miss the almost-forgotten Marquis Daniels, who is due back after the All-Star Game. He will have missed almost 30 games with a thumb injury.

The Lakers? They took advantage of a ridiculous, home-heavy schedule early in the season to break away from the rest of the West. They are 3-2 on their current Eastern swing, beating the tomato cans (New York, Washington and Philadelphia) while losing to Cleveland and Toronto. The Celtics are the third winning team they’ll face on the trip.

The defending champs have been very tough to beat with Pau Gasol in the lineup. The talented Spaniard has played in 30 games this season and the Lakers have won 25 of them by an average of 10 points a game. Gasol has missed 16 games with hamstring injuries and LA is 10-6 in those games.

Kobe Bryant, meanwhile, is poised to pass Jerry West as the all-time Lakers scoring leader. He is 47 points behind West and wouldn’t Bryant love to pass the man who drafted him against the team that so tortured his old boss in the 1960s? He averages 25.1 against the Celtics, but erupting for 48 would not be unBryant-like, even as he finishes up an uncharacteristically cold month for him (24 points a game versus more than 30 a game in November and December.)

The atmosphere in the Garden will be wall of sound stuff. The ‘Beat LA’ chants started here in the 1980s. But the Lakers won in Boston last season (110-109 in overtime) after getting beaten four times there the year before, including three in the NBA Finals. LA has won six of its last 10 regular season games in Boston, which is relatively unremarkable given how bad the Celtics were over most of that time period.

In the 1980s, these meetings were full of high drama and expectations. The two teams followed each other on a daily basis on the assumption they’d probably meet in the NBA Finals. ML Carr called them ‘The Fakers.’ The Fabulous Forum brought us Dancing Barry, the Rambis Youth and Randy Newman for the mood music. There were Hall of Famers at every position.

There is so much history here, from the great balloon story from Game 7 of the 1969 Finals (when Lakers owner Jack Kent Cooke had balloons ready for a title celebration that never came) to Kevin McHale’s series-changing takedown of Kurt Rambis in Game 4 of the 1984 Finals to Magic’s hook shot in Game 4 of the 1987 Finals.

They may have another Finals meeting and it might be this year. But that’s a long way from now. The real injustice is that they see each other only twice during the season. That’s what makes this one so appealing.