Leigh Steinberg, the sports superagent whose life the movie "Jerry Maguire" was based upon, is at the center of a real-life agency split up.

Steinberg and partner Jeff Moorad filed suit against David Dunn, claiming the third partner of the Steinberg, Moorad & Dunn sports management firm breached his contract by attempting to steal away as much as 80 percent of its high-profile clientele and forming a new agency.

According to the lawsuit, filed Tuesday in California Superior Court in Los Angeles, Dunn conspired to lure away most of SMD's 86 professional football clients to a competing firm -- Athletes First -- founded by Dunn in February. Both actions, the suit claims, are a breach of Dunn's contract with SMD.

The lawsuit claims SMD has received eight termination letters from players since Dunn's departure, including those from Patriots quarterback Drew Bledsoe, Bengals running back Corey Dillon, Titans defensive end Jevon Kearse, Cowboys defensive back Darren Woodson, Dolphins linebacker Derrick Rodgers, 49ers defensive tackle Reggie McGrew and Giants wide receiver Amani Toomer.

Some are believed to either have signed with Athletes First or were prompted by talks of Dunn's move to terminate their contracts with SMD, according to the suit. Kearse jumped ship to sign with another agent, Drew Rosenhaus, in March.

Steinberg and Moorad refused comment on Thursday. But Deanna Allen, a spokesperson for Assante Corp., the parent company of SMD, said the corporation "understands that keeping clients in the agent business is a hard task," and that Assante accounted for that by signing the firm's members to long-term contracts in November 1999. Dunn, according to the lawsuit, received a $2 million signing bonus at that time.

Dunn did not return a call from ESPN.com seeking comment.

Both Steinberg and Moorad had downplayed reports of Dunn's split with their agency. Just three weeks ago, Moorad told ESPN.com that Dunn was working closely with SMD and said if Dunn did start a new agency, it would fall under Assante's umbrella.

Since his departure from SMD, Dunn orchestrated Bledsoe's 10-year, $103 million deal with the Patriots, the biggest in NFL history, in March and helped Dillon sign a reported five-year, $30 million deal with the Bengals in May.

Darren Rovell, who covers sports business for ESPN.com, can be reached at darren.rovell@espn.com.