It has been four years since Miami took the league by storm, forming a most impressive Big Three on South Beach.

You know the names — LeBron James, Dwyane Wade and Chris Bosh. The goal this year is similar, only this time, the Heat are willing to settle for a much smaller three. The Heat need upgrades in free agency this summer, and they need them fast. The addition of three useful veterans is the goal.

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According to sources, among the players the Heat will pursue are veteran Warriors guard Steve Blake, who can play either guard spot, can knock down 3-pointers and is expected to draw interest from other contenders, like the Thunder.

Another pair of graybeards is also on the Heat list: Shawn Marion of the Mavericks and teammate Vince Carter. Both players have expressed in

terest in the team, and the feeling is said to be mutual.

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The Heat would like to add someone in his prime this summer, including Marvin Williams, Trevor Ariza or Kyle Lowry. But the fact is, there won’t be much available when it comes to players in their 20s, and the Heat can't go overboard with spending. DeJuan Blair is a possibility at power forward, while Spencer Hawes and Channing Frye are outside possibilities for the frontcourt.

Still, it is clear the Heat will be willing to spend in order to keep the team together. The James-Wade-Bosh trio met last week to discuss their strategy going forward, and with all three opting out of their contracts — plus James Jones and Udonis Haslem — the Heat have the flexibility to pursue new options.

The best way to do that, of course, is to apply pressure to the Heat front office, and the only weapon the Heat’s big trio has to do that is their contracts — free agency allows them the avenue to leave. They almost certainly won’t, but the hope is that the threat of their departure could be enough to force some moves.

“They want to keep the band together, so to speak,” the source said. “But what they need is better backup singers, better support. That was not there last year.”

While there has been some talk of major free-agent maneuvers, some have been overhyped. The prospect of Carmelo Anthony taking a major pay cut to join the Heat, for example, has little hope of coming to fruition.

The Heat have been linked to Lowry, too, but that is also a longshot. Lowry would like a major payday, and that’s not going to come with the Heat. It is likely to come from the Raptors, who are girding for a big Lowry contract, with the Lakers eager to upgrade quickly — as the next best bet.

Miami brass knows this. James, Bosh and Wade know this. “Some of the names you’ve heard,” the source said, “have been a little out of left field. Not totally impossible, but not realistic. Everybody involved knows they just need to add role players who can contribute.”

They had precious few of those when last year’s Finals came around. Outside of their Top 3 options, the Heat got contributions from Rashard Lewis and Ray Allen, but virtually no one else. The Spurs, meanwhile, had eight players who scored at least 30 points in the five Finals games.

Two players they had used extensively in their previous two championship runs — Shane Battier, Udonis Haslem and Mike Miller — had nothing left by last year’s Finals, and another (Mike Miller) was gone altogether, amnestied to Memphis. Throw in the postseason no-show by Mario Chalmers, who may well have played his final game in Miami, and the Heat roster had far too much dead weight.

The Heat also will seek to pull something out of rookie Shabazz Napier and swingman James Ennis, a second round pick who had been playing in Australia. Player development has not been a priority for the team, as it is in a win-now mode, but watching the Spurs get contributions from internally developed players like Patty Mills and Kawhi Leonard should push the Heat to work more on bringing along young guys.

The Heat are not expected to lose the Big Three this summer. Instead, they’re looking to add a small group of three around them.