The Brandon Rios-Yuriorkis Gamboa lightweight title bout, at risk for the past week after Gamboa skipped news conferences in Miami and Los Angeles because he was unhappy with a deal that promoter Top Rank said he had agreed to, was canceled late Tuesday.

The high-profile fight was supposed to headline an HBO "World Championship Boxing" card April 14 from Mandalay Bay in Las Vegas, but the network pulled the plug on the show when it could not reach an agreement with Top Rank on a replacement opponent to face Rios. HBO will not have any boxing on the date.

However, Top Rank said that Rios will still fight April 14 at Mandalay Bay, even without HBO's backing. HBO had agreed to pay more than $2 million for Rios-Gamboa.

"Brandon will be fighting April 14 and we are working on the details now," Top Rank spokesman Lee Samuels told ESPN.com on Wednesday. "There will be a fight April 14."

Top Rank has not yet announced television plans for the card.

Also on Tuesday, Top Rank filed a breach of contract suit against Gamboa in U.S. federal court in Nevada, seeking to have its contract with Gamboa upheld.

In the suit, a copy of which was obtained by ESPN.com, Top Rank claims that "on or around Feb. 16 Gamboa explicitly agreed to all material terms of a contract to fight Rios on April 14, 2012, including the date, opponent, travel arrangements, purses and advances. After agreeing to fight Rios, Gamboa requested, received and accepted in excess of $70,000 in advances from Top Rank and (co-promoter) Arena in anticipation of the Rios bout."

The suit was also filed against "John Does 1 through 10" because Top Rank alleges that "one or more rival boxing promotion companies and unknown individuals associated with them are at the root of Gamboa's wrongful conduct."

When Gamboa skipped the Miami news conference he was in Las Vegas training at Floyd Mayweather Jr.'s gym, leading to speculation that Mayweather Promotions is trying to sign him out from under Top Rank and Arena Box.

Top Rank declined to comment on the suit. Sekou Gary, Gamboa's attorney, could not be reached for comment.

Samuels said that the junior welterweight fight between Mike Alvarado (32-0, 23 KOs) and Mauricio Herrera (18-1, 7 KOs), which was scheduled to open the HBO telecast, will go on as planned on the reshaped card.

"Brandon is disappointed. He's mad. He's hurt. All those emotions," Cameron Dunkin, Rios' manager, told ESPN.com. "He was really looking forward it. It's a shame, but he's gonna fight."

Dunkin said they had not nailed down an opponent yet, but that he was working on it with Top Rank executives Todd duBoef and Carl Moretti.

Richard Abril (17-2-1, 8 KOs), who holds an interim lightweight title, is the leading candidate, Dunkin said. Abril, a Cuban living in Miami, got into a heated argument with Rios (29-0-1, 22 KOs) at last week's Miami news conference, which had been planned for that city because it is where Gamboa, also a Cuban, lives. Abril also holds the WBA's interim belt while Rios and Gamboa were scheduled to fight for the vacant full title.

"He's a big possibility, probably the leading candidate, but it's not done yet," Dunkin said of Abril. "We don't know what we're doing yet. I need to still talk with Todd and Carl and we'll figure it out. I gotta tell them what I want to do and I need to hear what they want to do. I had a long talk with Brandon and (trainer) Robert Garcia about it (Tuesday) night. They are just disappointed because they want to fight and they wanted to fight Gamboa."

Dunkin said he was disappointed that Top Rank and HBO could not work out a new deal for a new opponent -- which would have cost the network a lot less than it had agreed to pay for Rios-Gamboa.

"I'm never mad at HBO. They're the buyers. They buy what they want to buy," Dunkin said. "Do I agree with them on this? No, I don't agree with them. But it's their choice and their network. All I can do is go sign the best fighters in the world and get them with the best people in the world and the best promotion in the world and I've done that. I don't know how you don't like Brandon Rios. I'm stumbling for words.

"I don't know how you pass on Brandon Rios against anyone. He'll make a fun fight every time out, so it's a shame. He loves to fight and he gives it everything he's got. But if they don't want it, they don't want it. It's a bad situation, but it's boxing."

Gamboa (21-0, 16 KOs), a 2004 Olympic gold medalist and former unified featherweight titlist, was due to move up two weight classes to face Rios for a vacant 135-pound title in the showdown between two of boxing's most exciting fighters.

However, only minutes before last Monday's kickoff news conference in Miami, Top Rank was notified that Gamboa would not attend, even though, according to duBoef, it was Gamboa who had requested a news conference in his adopted hometown.

Gamboa also was a no-show the following day in Los Angeles. Instead, he was training at Mayweather's gym in Las Vegas but boycotting the news conference because he said he was not satisfied with the deal for the fight from Top Rank and co-promoter Ahmet Oner of Arena Box.

DuBoef said Top Rank not only has a solid promotional agreement with Gamboa, but also proof that he had agreed to the terms for the fight with Rios, even though no bout agreement had been signed yet. It is standard practice for fights to be agreed to and promotions launched before bout agreements are finalized.

At the Los Angles news conference, duBoef went so far as to offer a $100,000 bonus to the winner of the fight on top of their seven-figure purses in the hope that Gamboa would change his mind.