After taking Smith’s belt, Canelo continue to hunt order championship belts and he
wanted it fast. He was a man on a mission on 2021 having fought three boxers and
concluding it by being the undisputed super middleweight champion.
On January 20, 2021, it was announced that Avarez would defend his belts on February
27 at the Hard Rock Stadium in Miami Gardens, Florida, against WBC mandatory
challenger Avni Yildirim. Many saw Yildirim, who had not been in the ring since losing a
technical split decision to Anthony Dirrell two years before in February 2019, as grossly
outmatched. Due to the contentious nature of his loss to Dirrell, Yildirim had been
named to the obligatory post, but he had stayed inactive due to injury and the COVID-
19 pandemic.
Avarez, who was forced to battle Yildirim despite being heavily favored, dismissed the
critics, stating, \”I really don\’t have to provide any explanation because they\’re never
going to be satisfied with anything… He [Yildirim] has a lot of courage. He can be
dangerous at any time because he is a strong fighter.\”
In a one-sided fight, Álvarez defeated Yıldırım by third-round corner retirement after
Yıldırım\’s corner threw in the towel at the end of the third round. According to
CompuBox stats, Álvarez outlanded Yıldırım 67 (40%) to 11 (11%) in total punches and
58 (59%) to 4 (22%) in power punches. In the third round, Álvarez threw 53 power
punches, Álvarez later stated that he had contracted COVID-19 prior to the fight and
only had one month to train.
After Álvarez\’s successful defense against  Avni Yıldırım , promoter Eddie
Hearn confirmed Álvarez would be facing WBO titleholder and undefeated two-weight
world champion Billy Joe Saunders in a unification bout on May 8 at the AT&T
Stadium in Arlington, Texas.
In front of a record breaking crowd of 73,126 for boxing attendance at an indoor facility
in the United States, Álvarez won via eighth-round corner retirement when Saunders\’
team threw in the towel due to Saunders having suffered a fractured orbital bone as a
result of an uppercut landed by Álvarez. At the time of the stoppage, Álvarez was
winning on the scorecards 78–74 (twice) and 77–75.Throughout the fight, Álvarez
outlanded Saunders 73 to 60 in total punches and landed 53% of his power punches.
After months of negotiations, Álvarez announced on his social media on 19 August
2021 that he would be facing undefeated IBF champion Caleb Plant on 6 November at
the MGM Grand Garden Arena in Las Vegas, in an undisputed showdown for all four
major world titles in the super middleweight division, with the winner set to become the
first ever undisputed champion at that weight class. On 21 September 2021, the two
fighters were engaged in a brief onstage scuffle during their first press conference, in
which Álvarez initiated physical contact during their face-off when he shoved Plant.
Álvarez stated that he had done this because he took offense to Plant\’s use of the word
\”motherfucker\”, interpreting it as an insult to his mother. 
On fight night, Álvarez won the bout via eleventh-round technical knockout. He had
knocked his opponent to the canvas with a left hook right uppercut combination in the
penultimate round, before closing in to drop Plant again, prompting referee Russell
Mora to call off the bout. At the time of the stoppage, Álvarez was ahead on the
scorecards with 98–92, 96–94, and 97–93. With this win, he became only the sixth
fighter to unify all belts in one division in the four-belt era.