The Ring has learned that an agreement is in place for Saul “Canelo” Alvarez to defend his super middleweight titles against Terence Crawford in an intriguing battle between generational greats.

Alvarez, 34, and Crawford, 37, are expected to meet in the main event of a Riyadh Season show - on a September date to be determined, and a venue to be chosen in Las Vegas.

The Alvarez-Crawford megafight will pit the No. 3 fighter on The Ring’s pound-for-pound list, Crawford, against the seventh-rated Alvarez, boxing’s most marketable star in the United States.

Crawford (41-0, 31 KOs), of Omaha, Nebraska, and Alvarez (62-2-2, 39 KOs), of Guadalajara, Mexico, are four-division champions and elite-level talents, but Crawford will move up two weight classes – from the junior middleweight limit of 154 pounds to the super middleweight maximum of 168 – for what figures to be the most difficult fight of his 17-year professional career.

Alvarez and Crawford both stand at approximately 5-foot-8, but Alvarez figures to open as a decided betting favorite because he is the more powerful fighter and has competed as high as the light heavyweight limit of 175 pounds.

Crawford made his junior middleweight debut August 3, when career-long 154-pound contender Israil Madrimov (10-1-1, 7 KOs) gave Crawford some trouble in a 12-round bout the former undisputed welterweight champ won by unanimous decision at BMO Stadium in Los Angeles.

The business savvy Alvarez initially ignored Crawford’s overtures. As momentum developed for their fight among hardcore and casual boxing fans, Alvarez eventually came around.

The Mexican superstar and Turki Alalshikh - owner of The Ring and head of Riyadh Season - met in London last month to discuss the Crawford bout because Alvarez attended the inaugural Ring awards gala at Old Royal Naval College.

Crawford has long been committed to moving up two weight classes to square off against Alvarez in what has all the makings of a very successful pay-per-view event.

Alvarez - who holds the Ring, IBO, WBA, WBC and WBO super middleweight titles - is first expected to fight May 3 at T-Mobile Arena in Las Vegas. His opponent for what will amount to a stay-busy fight prior to facing Crawford has not been determined.

IBF super middleweight champ William Scull (23-0, 9 KOs) has long been considered as a possible option for Canelo's return in May.

Scull won the IBF belt stripped from Alvarez last July on October 19. The Cuban-born, Germany-based Scull defeated Russia’s Vladimir Shishkin (16-1, 10 KOs) by unanimous decision that night at Stadthalle in Falkensee, a suburb of Berlin.

It isn’t clear if Crawford will box before a fight with Alvarez in September. If Crawford waits, he won’t have fought for 13 months by the time he steps into the ring to box Alvarez.

Crawford has history on his side, because unlike most championship-caliber boxers, he has performed at an elite level even when ending long periods of inactivity.