The resignation of Randy Couture (Pictures) and his subsequent continuous dispute with the UFC took an unexpected turn Wednesday.

With the mixed martial arts industry focused on the Zuffa v. Couture proceedings scheduled to begin with a preliminary hearing March 4 in Las Vegas, billionaire Mark Cuban and his HDNet Fights company has quietly entered the fray, opening a second front in the Couture-UFC war, Sherdog.com has learned.

On Wednesday, in district court in Dallas, HDNet Fights filed suit against Zuffa seeking a declaratory judgment concerning the contractual status of Couture under his Zuffa promotional contract. In an ironic twist, Zuffa's co-defendant in the suit is technically none other than Couture himself.

Couture had fired the first shot in what has become a heated legal battle when he officially resigned from the UFC on Oct. 11, 2007. A war of words ensued -- complete with dueling news conferences and frequent, often testy, verbal sparring in the media -- that culminated in a lawsuit filed by Zuffa in Nevada district court on Jan. 14.

The lawsuit filed by HDNet Fights asks the Texas court to provide the company with declaratory relief -- a ruling on when Couture's promotional contract will expire. A favorable ruling could clear the way for a highly anticipated showdown between Couture and Fedor Emelianenko (Pictures) this fall, potentially promoted by HDNet Fights.

The Texas lawsuit represents the first direct legal challenge of Couture's promotional contract with the UFC. As Sherdog.com first reported, it is Couture's employment contract and its one-year non-compete clause, not his promotional contract, that is at the center of Zuffa's complaint against Couture in Nevada. Zuffa has not entered the promotional contract into evidence in that case; however, it has offered the judge the opportunity to view it in private.

Couture's contractual status, pursuant to his promotional contract, has been hotly debated since his resignation. UFC President Dana White has been resolute in his stance that Couture owes the UFC two more fights due to a so-called "retirement clause" reportedly found in Couture's contract.

In a letter made public in recent court filings, White responded to Couture's resignation: "With regard to your fighting career, I presume that your letter refers to your Exclusive Promotional and Ancillary Rights Agreement dated January 19, 2007 ("Agreement"). Pursuant to Section 10.3 of the Agreement, I presume that you have decided to ‘retire' from MMA or other professional fighting competition. Assuming that is your intention, Zuffa, LLC is electing to suspend the Term of the Agreement for the period of such retirement."

Couture has stated publicly that he believes his promotional contract expires at the end of its term, believed to be 18 months. If that is the case, following the expiration of the non-compete clause in his employment contract in October, he would be free to fight outside the UFC this fall.

Adam Swift is the Editor of MMAPayout.com and a regular contributor to Sherdog.com.