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UPDATE: The Toronto Raptors are not working on a sign-and-trade with the Miami Heat involving point guard Kyle Lowry, a high-ranking Raptors source said Friday night, shortly after the publication of the story below, which proposed a deal was "Imminent."

ORIGINAL TEXT: An agreement in principle on a deal that would send point guard Kyle Lowry from the Toronto Raptors to the Miami Heat is "imminent," a league source with direct knowledge of the negotiations said Friday.

The deal, which will consist of the Raptors signing and trading Lowry in exchange for Heat point guard Norris Cole, cash and a combination of future draft picks, can't be officially consummated until sometime after July 1 because Miami is currently over the salary cap and must sort out its position with its existing core of superstars—LeBron James, Dwyane Wade and Chris Bosh.

But James already has opted out of the remaining two years of his Heat contract and the team is aggressively looking to upgrade its point-guard position to persuade James to return. Miami traded up to acquire University of Connecticut point guard Shabazz Napier in Thursday night's NBA draft, but apparently aren't stopping there to show James he will not have to carry the same ball-handling and playmaking duties as he did during the team's failed attempt to snare a third consecutive championship this past season.

Regardless of how the discussions go with James, Wade and Bosh, however, "Lowry will be a member of the Heat" next season, the source said. The Heat's grand plan is to transform its Big Three into a Big Four that would include Knicks free agent Carmelo Anthony, multiple league sources have said. The addition of Lowry, though, could mean only part of the current Big Three comprises the new quartet.

Lowry, a nine-year veteran, put up career highs in points (17.9 per game), assists (7.4), rebounds (4.7) and starts (79) to help Toronto make the playoffs for the first time since 2008 with a franchise-record 48 wins. The exact terms of his deal are being worked out, but its value will be $9-$10 million a year for at least three years. He made roughly $6.2 million this past season.

Ongoing concerns within the Raptors organization that Lowry's notable improvement was inspired by his pending free agency and mutual interest between Lowry and the Heat prompted the three parties—Toronto, Miami and Lowry—to work toward a mutually beneficial agreement.

“I'm happy with making the playoffs and doing that, but the end game for all players should be a championship and that's what I want to play for," Lowry told Basketball Insiders this week. "I want to play for a championship.”

Coming to terms on a deal as early as possible allows both teams to know exactly where they stand and act quickly when free agency begins.

Raptors general manager Masai Ujiri knows all too well the perils of going into the summer uncertain about a superstar with an expiring contract. He served as an assistant GM when Chris Bosh bolted Toronto to join James and Wade in Miami in 2010. Shortly thereafter he was hired away by the Denver Nuggets as their VP of basketball operations and presided over dealing presumptive free agent Carmelo Anthony to the New York Knicks less than a year later.

Bosh now is expected to follow James into free agency by opting out of the remaining two years of his Heat contract, the source said, and the Raptors intend to meet with him to gauge his interest in returning to Toronto.

The attraction for Bosh to Toronto would be a more significant role and a longer-term deal with the Raptors. Were he to stay in Miami and the pursuit of Anthony prove successful, Bosh would be looking at a significant pay cut and remaining the third option, if not possibly sliding to the fourth, offensively. Bosh has repeatedly stated that he'd like to stay in Miami, but rival GMs and executives have indicated that if the Heat's current Big Three were broken up, they have believed that Bosh would be the one to leave.

Ric Bucher covers the NBA for Bleacher Report.