Gennadiy Golovkin will be paid handsomely if he and Canelo Alvarez handle their business in upcoming bouts and finally fight again September 17.

Meanwhile, the longtime middleweight champion understandably still wants what he and his team contend he is owed from their second fight in September 2018.

BoxingScene.com has learned that attorneys filed a lawsuit Friday on Golovkin’s behalf against Golden Boy Promotions in the State Superior Court of California. Their rematch took place in Las Vegas, but the lone named defendant, Oscar De La Hoya’s promotional company, is headquartered in Los Angeles.

The suit was filed in the County of Los Angeles’ Central District. The civil complaint alleges breach of contract, breach of fiduciary duty, conversion, constructive trust and accounting, and demands a jury trial.

In the suit, Golovkin seeks “not less than $3 million” in damages from Golden Boy for profits owed mostly from gate receipts and sponsorships. Golovkin also wants interest on the $9,025,351 it took Golden Boy nearly three years after the fight to pay him.

Golden Boy made its final installment on that debt last July 6.

According to the suit, a copy of which was obtained by BoxingScene.com, Golovkin is owed an additional $1,375,000 from gate receipts, a minimum of $450,000 from sponsorships for that HBO Pay-Per-View event, $31,500 in pay-per-view upside (45 percent), funds deducted as an expense from the postponement of the fight (due to Alvarez twice testing positive for a performance-enhancing drug in February 2018), unapportioned insurance expenses, “other funds simply not paid though listed on Golden Boy’s own accountings” in the amount of $177,458 and interest on the $9,025,351 it eventually paid in full.

Golovkin’s lawyers referred to Golden Boy’s deferred payments on the aforementioned $9 million-plus as “an interest-free loan” in court documents. The suit states that Golden Boy acknowledged in January 2021 that it owed Golovkin that enormous sum of money, but that it “had used that money for other purposes” and repeatedly broke promises to make payments on the full amount.

Nearly half of the damages sought by Golovkin stem from what is called Golden Boy’s “revised accounting” last September 27 of proceeds from ticket revenue. In contracts for their rematch, Golden Boy was entitled to 55 percent of ticket revenue and Golovkin was supposed to receive 45 percent.

Golden Boy has “refused to pay” Golovkin that additional $1,375,000, according to court documents, despite “clear contract language” that entitles him to that amount.

According to the Nevada State Athletic Commission, the Alvarez-Golovkin rematch generated $24,573,500 in ticket revenue. It stands as the fourth highest-grossing gate for boxing in Nevada history, behind only Floyd Mayweather-Manny Pacquiao ($72,198,500), Mayweather-Conor McGregor ($55,414,865.79) and the first Alvarez-Golovkin fight ($27,059,850).

This lawsuit shouldn’t in any way prohibit Golovkin, 39, and Alvarez, 31, from moving forward with their third fight. Alvarez, who is not named in the suit, parted ways with Golden Boy due to his own contract dispute in the fall of 2020.

Their third fight would be co-promoted by Eddie Hearn’s Matchroom Boxing, Alvarez’s promotional partner, and Golovkin’s company.

For the rivals to fight a third time, Golovkin (41-1-1, 36 KOs) and Alvarez (57-1-2, 39 KOs) need to win middleweight and light heavyweight title fights scheduled four weeks apart in April and May.

Golovkin, the IBF 160-pound champion, is set to battle Japan’s Ryota Murata (16-2, 13 KOs), the WBA middleweight champ, on April 9 at Saitama Arena in Saitama, Japan. Alvarez, the fully unified super middleweight champion, is slated to move back up to the light heavyweight division to box WBA champ Dmitry Bivol (19-0, 11 KOs) on May 7 at T-Mobile Arena in Las Vegas.

DAZN will stream the Golovkin-Murata and Alvarez-Bivol bouts worldwide. There is an agreement in place for their long-discussed third fight to place four months after Alvarez-Bivol if Golovkin and Alvarez win those two fights.

Alvarez left Golovkin with his only professional loss when he won a majority decision in their 12-round rematch 3½ years ago at T-Mobile Arena in Las Vegas.

The result of their first fight, a 12-round split draw in September 2017 at T-Mobile Arena, caused controversy in large part because judge Adalaide Byrd scored 10 of the 12 rounds in what was a completely competitive fight for Alvarez, 118-110. Judge Dave Moretti scored Golovkin a 115-113 winner over Alvarez that night, but judge Don Trella had it even, 114-114.

Keith Idec is a senior writer/columnist for BoxingScene.com. He can be reached on Twitter @Idecboxing.