Bill Duffy, the agent for Miami Heat guard Anthony Carter, told ESPN.com on Monday that a clerical error in his office led to the missed contract deadline that threatens to cost Carter the bulk of his $4.1 million salary next season.

Carter was required to notify the Heat by June 30 that he intended to invoke the player option on the final season of his original three-year, $12 million contract. When the Heat received no such notification, the NBA officially listed Carter as a free agent Tuesday -- the first day teams were permitted to negotiate with free agents.

If Miami renounces its rights to Carter, it could have closer to $11 million in available salary cap room than the $7 million previously estimated -- a difference expected to immediately transform the Heat into a major player on this summer's free-agent market.

"I feel sick for the person in our office who was responsible (for monitoring Carter's situation and contacting the Heat) and he feels sick about it," Duffy said. "This is obviously an unfortunate situation, but it's my name on the company and I'll take responsibility for it."

Duffy, who refused to name the employee, ranks as one of the league's most well-respected agents, with a client list featuring three of the top four picks in the 2002 draft: Houston's Yao Ming, Chicago's Jay Williams and Orlando's Drew Gooden. In October, Duffy was named one of the NBA's top 25 "shapers and shakers" by ESPN The Magazine.

It remains to be seen how the Heat will proceed in response to the Carter camp's costly mistake or the potential windfall that stems from the error. Carter's contract previously had been regarded as one of the main impediments to Miami making a free-agent splash, since his production last season -- 4.1 points per game on 35.6-percent shooting -- is not commensurate with a $4 million player.

Renouncing its rights to Carter and center Alonzo Mourning, who is expected to sign with Dallas or another championship contender, would provide Heat coach and president Pat Riley with the financial wherewithal to pursue Golden State point guard Gilbert Arenas, or perhaps Los Angeles Clippers restricted free agent Lamar Odom. Milwaukee guard Gary Payton has also expressed interest in Miami, if his talks with the Los Angeles Lakers dissolve. Two more possibilities: Miami could try to split their money between two younger free agents, or save the cap room in hopes of creating even more space for the summer of 2004.

To further muddle matters, another Duffy client, Clippers center Michael Olowokandi, is high on Miami's wish list in any scenario. If Olowokandi signs with the Heat this summer, the contract figures to attract added scrutiny from the league office.

Of course, there remains a chance that the Heat could take a benevolent stance and offer to re-sign Carter at a reduced rate. That would still create some extra salary cap room but could also help Carter recoup some of the money he is certain to lose. On the open market, it's highly unlikely that Carter could command anything more than the $688,679 league-minimum salary for players with four seasons of experience.

"There's a very good relationship between BDA Sports Management and the Miami Heat," Duffy said. "I think they hold AC in high regard as a player and a person, and we're optimistic that we can reach an honorable solution."

Heat officials declined comment Monday. Carter is in Atlanta and could not be reached.

Marc Stein is the senior NBA writer for ESPN.com. To e-mail him, click here. Also, send Stein a question for possible use on ESPNEWS.