The six-month NBA marathon has come down to a nine-day sprint with fewer than half the league’s 16 playoff spots resolved. Let’s look at what’s at stake and who should prevail in the season’s final days.

WESTERN CONFERENCE NO. 1

Southwest Division and longtime intrastate rivals the San Antonio Spurs (59-18) and Dallas Mavericks (58-19 entering last night’s action) have finished either tied or separated by one game in three of the last four seasons, so it’s no surprise that the two are heading down the stretch one game apart. At stake is the conference’s top seed, with the loser falling to the fourth seed behind the champions of the Pacific and Northwest Divisions.

The major prize isn’t necessarily an easier first-round series because Sacramento, one of the league’s most improved teams during the second half of the season, may await the winner as the eighth seed. However, a second-round matchup between the Texas powers looms, and whichever wins the Southwest Division will enjoy homecourt advantage in what figures to be a close, hard-fought series.

Dallas’s remaining schedule includes road games in Utah and Phoenix, followed by home tilts against Utah on Sunday and the L.A. Clippers in the regular season finale. Given that the Suns are slumping since Kurt Thomas’s injury,the Mavericks could easily run the table,but they will probably still finish behind the Spurs. San Antonio might look vulnerable following consecutive home defeats to Sacramento and Dallas last week and a close win over Memphis on Sunday,but the Spurs’ remaining slate is especially easy. Only Thursday night’s game in San Antonio against the suddenly hot Orlando Magic looks difficult.

Look for the Spurs to maintain their lead and enjoy the home court for a seven-game, second-round series against their in-state rival to the north.

WESTERN CONFERENCE NO. 5 AND NO. 6

The Clippers (44-32) and the Memphis Grizzlies (44-33) have already punched their tickets to the postseason, but each would probably like to graciously lose the battle for the no. 5 seed. Dallas or San Antonio awaits the winner, while the loser not only gets to face Denver (43-34),but may have home court advantage in the series as well.Talk about winning for losing.

Both teams are surprises. The Clippers have been doormats for so long that their team name is synonymous with incompetence, but this season, led by Elton Brand’s stellar play (24.9 points and 10.1 boards per game on 52.7% shooting) and the league’s seventh-best defense (104.8 points allowed per 100 possessions), L.A. has soared into the middle of the playoff picture.

Most pundits felt that Memphis had weakened itself with off-season moves that dispatched point guards Earl Watson and Jason Williams and small forward James Posey. New additions Bobby Jackson and Eddie Jones are older, but have played solid ball and enabled the Grizzlies to maintain their trademark tight defense (their Defensive Efficiency rating of 103.8 ranks third in the league.) We’ll see how quickly the Clippers and Grizzlies bench the regulars when the two meet next Tuesday in Memphis.

WESTERN CONFERENCE NO. 7 AND NO. 8

Two other bitter in-state rivals, Sacramento and the Los Angeles Lakers, (both 41-37) are dueling for position for the final two playoff spots in the West. There’s more than just regional pride at stake, too. The seventh seed will draw a beatable Phoenix team,while the eighth seed will get the much tougher winner of the San Antonio-Dallas race.

The Lakers and Kings are tied in the standings and split their four games this season, but the Kings own the tiebreakers for division and conference records. The Lakers’ final four games are at home, but the Kings’ schedule is softer. Utah and New Orleans/Oklahoma City (both 37-39) are also in the mix, but they’ll need to run the table and hope for an injury either to the Lakers’ Kobe Bryant or the Kings’ Ron Artest before they have a serious chance of crashing the party.

EASTERN CONFERENCE NOS. 6-8

The bottom of the Eastern Conference bracket always seems to consist of teams that are “playoff caliber” by dint of league rules rather than any intrinsic quality, and this year is no exception. Milwaukee (37-40), Indiana (36-40), Chicago (35-41), and Philadelphia (35-41) are all vying for the right to be someone’s first-round victim.

The mystery is what the Pacers are doing here. They’ve suffered through a series of injuries all season that have prevented them from contending for the top spots, but they enter the final stretch of the season on a 2-8 slide. All their peripheral numbers suggest the Pacers are a much better team than their record. The departure of Artest hasn’t hurt their typically rugged defense, which ranks fourth in the league in Defensive Efficiency at 104.1. Most of the evidence suggests that the Pacers, with remaining games against Boston, Minnesota, Charlotte, Toronto, and Orlando, will turn it around and overtake Milwaukee for sixth place in the conference.

The other three teams should be viewed in terms of which is most likely to fall out of the picture.The Bucks have rebounded nicely from last year’s 30-52 debacle, but their five remaining games include three against teams with winning records, so they are in some danger of losing their seeding.

The Bulls have struggled all season, but their defense has turned it up big time in recent weeks, rising from middle of the pack to sixth in Defensive Efficiency at 104.5. They’ve won six of 10 – which, relative to their competition, is a hot streak – and three of their six remaining opponents have winning records, so the Bulls will have to maintain their improved play to secure a playoff berth. That will hinge on the speedy return of forward Luol Deng, their most consistent player, who suffered a concussion in practice on Saturday.

It’s hard to imagine the playoffs without Allen Iverson, but his 76ers face the conference’s toughest challenge. Three of their remaining five opponents sport winning records, and power forward Chris Webber has been hobbled by an assortment of injuries.The Sixers also lose the tie-breaker with the Bulls, with whom they are presently tied for the final spot. Iverson will do everything possible to will his team forward, but even in this weak field, it probably won’t be enough.

mjohnson@nysun.com