By Jake Donovan

Miguel Cotto and Saul 'Canelo' Alvarez collide Saturday evening at Mandalay Bay in Las Vegas, with the World midldeweight championship at stake. 

The pair of boxing superstars both met the terms of the contracted 155 lb. catchweight limit. Cotto weighed 153.5 lbs., the second straight fight where he came in light enough to fight at the super welterweight limit despite reigning as the World middleweight champion. Alvarez came in right at the 155 lb. mark, his fourth straight fight at that contracted weight.

Their main event bout will air live on HBO Pay-Per-View (Saturday, 9:00 p.m. ET/6:00 p.m. PT).

Cotto (40-4, 33KOs) attempts the second defense of his World middleweight champion. He won the crown with a 10th round stoppage of Sergio Martinez last June, becoming the first ever fighter from Puerto Rico to claim titles in four separate weight classes. 

His lone defense came in June, knocking out former titlist Daniel Geale in four rounds. The bout was his only defense of the WBC title, as the Mexico-based sanctioning body stripped Cotto of the belt earlier this week for failure to agree to pay the necessary sanctioning fees. 

The green belt remains at stake for Alvarez, though Cotto is still recognized as the lineal champion and will retain such honors with a win. Should Alvarez emerge victorious, he will not only claim the WBC belt but also gain recognition as the first-ever boxer from Mexico to win the lineal middleweight crown. 

Alvarez - a former super welterweight titlist - comes in on the heels of a violent 3rd round knockout of James Kirkland in May. The bout marked his triumphant return to HBO after a five fight stint with Showtime, celebrated in grand fashion with more than 30,000 in attendance and 2.1 million home viewers.  

In the chief support, Takashi Miura travels from Japan to put his super featherweight title on the line versus unbeaten Francisco Vargas. Miura (29-2-2, 22KOs) weighed in right at the 130 lb. limit in attempting the fifth defense of his title. Vargas (22-0-1, 16KOs) weighed 129.5 lbs. for his first career title fight. 

Guillermo Rigondeaux (15-0, 10KOs) enjoys a celebrated return to the ring as he faces Philippines' Drian Francisco in a World super bantamweight championship bout. Despite the fight being added less than a week ago, both fighters were well within the contracted limit. Francisco (28-3-1, 22KOs) weighed 121 lbs., while Rigondeaux weighed 121.5 lbs. for his first fight since last New Year's Eve.

Opening the PPV telecast, Jayson Velez (23-0-1, 16KOs) faces Ronny Rios (24-1, 10KOs) in a 10-round featherweight bout. Both fighters weighed in at 125.5 lbs. 

Featured on the "freeview" portion of the card, Randy Caballero returns to the ring following a year-long forced break due to injury. The unbeaten Californian was forced to leave his bantamweight title at the scales, however, after showing up at 123.5 lbs, more than a full division above the limit. 

Because the weight was so far above the contracted limt, Caballero (22-0, 13KOs) was forced to vacate his belt at the scales. It will still be at stake for Lee Haskins (32-3, 14KOs), who weighed 117.5 lbs. The interim titlist from England comes in on the heels of a thrilling 6th round knockout of Ryosuke Iwasa in June. 

FULL WEIGHTS

Miguel Cotto vs. Saul Alvarez - 12 rds, middleweight (155 lb. catchweight)

Takashi Miura, 130 lbs vs. Francisco Vargas, 129.5 lbs - 12 rds, super featherweight

Guillermo Rigondeaux, 121.5 lbs. vs. Drian Francisco, 121 lbs. - 12 rds, super bantamweight

Jayson Velez, 125.5 lbs. vs. Ronny Rios, 125.5 lbs. - 10 rds, featherweight

Randy Caballero, 123.5 lbs.* vs. Lee Haskins, 117.5 lbs. - 12 rds, bantamweight

Zhilei Zhang, 264.5 lbs. vs. Juan Goode, 244 lbs. - 4 rds, heavyweight

*Caballero is 5.5 lbs. above the bantamweight limit and has been forced to vacate bantamweight title, now at stake only for Haskins

Jake Donovan is the managing editor of BoxingScene.com. Twitter: @JakeNDaBox