No longer confident they can win a championship with their current roster, the Phoenix Suns are close to completing a blockbuster trade that will bring them Shaquille O'Neal, a source with knowledge of the negotiations said Tuesday.

O'Neal is scheduled to travel to Phoenix aboard a private plane Wednesday and undergo an MRI on his left hip, the source said. If he passes the physical, the Suns are expected to send Shawn Marion and Marcus Banks to the Miami Heat.

The Miami Herald first reported the Suns and Heat were in serious trade discussions involving O'Neal.

Frustrated by Miami's dramatic dropoff this season - the Heat own the NBA's worst record at 9-37 - O'Neal had begun telling teammates he wanted to be traded but never thought a deal would come to fruition, a Heat source said. O'Neal has missed 14 games this season and is sidelined with bursitis in his left hip.

The trade would represent a dramatic change for the Suns, whose run-and-gun, small-ball style had revolutionized the league in recent seasons. That same style, however, has failed to bring the Suns a championship, and team officials have become increasingly skeptical about their chances of contending without giving Amare Stoudemire some help on the frontline - even though Phoenix owns the Western Conference's best record at 34-14.

While praising recent improvement in Stoudemire's defense, Suns general manager Steve Kerr said last week the team still was doing Stoudemire a "disservice" by playing him at center instead of his more natural power forward position.

While last week's loss to a San Antonio Spurs team missing Tony Parker again raised some doubts, it was the Los Angeles Lakers' acquisition of forward Pau Gasol from the Memphis Grizzlies on Friday that ultimately spurred the Suns to consider aggressively looking for another big man. League sources said the Suns also had conversations about the Charlotte Bobcats' Emeka Okafor and the Philadelphia 76ers' Samuel Dalembert in recent days, but that Miami initiated the trade talks involving O'Neal.

O'Neal, 35, still is a physical presence but seems a poor fit for Phoenix coach Mike D'Antoni's up-tempo offense. Suns coaches, however, watched film of O'Neal on Tuesday, the source said, and came away thinking O'Neal's strong passing skills from the high post would work well in their half-court schemes. The Suns also have shown increasingly more confidence in playing forward Boris Diaw next to Stoudemire and think that combination will suffice when O'Neal isn't on the floor.

Phoenix doesn't expect O'Neal to keep pace with its transition offense and plans to utilize him as an inbound and outlet passer. His greatest contributions, the Suns hope, will come on the boards and defense, two areas of Stoudemire's game that are lacking.

If completed, the trade will have huge financial ramifications for the Suns. O'Neal has two years and $40 million left on his contract after this season. Banks, who never has earned enough of D'Antoni's trust to become a regular member of the team's rotation, has three seasons and $13.7 million remaining on his deal. Marion has one more season worth $17.8 million but can opt out of the contract and become a free agent this summer.

The Suns have worked to avoid paying a hefty luxury-tax bill, going so far as to trade center Kurt Thomas, their best low-post defender, and two first-round draft picks to Seattle in July just to get Thomas' $8 million salary off their payroll. Trading for O'Neal would give the Suns a 2½-season window to challenge for a championship before the contracts of O'Neal and soon-to-be 34-year-old point guard Steve Nash both expire in the summer of 2010, removing more than $33 million from the team's salary cap.

The Suns also have wanted to address chemistry problems in their locker room. Marion long has felt he doesn't get the respect he deserves - or at least not on par with that of Nash and Stoudemire - and asked to be traded after Kerr turned down his request for a three-year, $60 million extension shortly before the season. Stoudemire also complained last month about not getting enough shots.

The trade's benefits for the Heat are obvious: With this season already lost, they get O'Neal's hefty contract off the books and the chance to free up cap room if they don't sign Marion to an extension. Banks also could become the point guard for which Miami has been searching nearly all season.

News of the pending trade sent shockwaves through a Western Conference landscape still shifting after Gasol's trade to the Lakers. League executives were stunned the Suns even would seriously contemplate such a move, let alone agree to it, given O'Neal's declining production and enormous contract.

Two of Phoenix's biggest rivals, the Spurs and Dallas Mavericks, now are adept at playing small because they had to learn how to match up with the Suns. If the trade is completed, the Suns, in a bizarre change of events, could find themselves having to match down with some of their opponents.

Said one West executive: "I truly thought this was a joke."