The fight for the middleweight world championship took place at the T-Mobile Arena in Las Vegas, Nevada on 15 September 2018. Canelo Alvarez held the Ring Magazine title and was lineal middleweight champion. Gennady Golovkin was the undefeated middleweight world champion of the WBC, WBA (Super), IBF and IBO associations. Alvarez won by a majority decision (115-113, 115-113, 114-114).

This fight was a rematch of their first fight of 16 September 2017, which ended in a disputed draw. Originally, the rematch was planned for 5 May 2018. However, Canelo tested positive for banned substances and was suspended for six months. According to Canelo, he had unknowingly ingested the substances through contaminated meat in Mexico. Golovkin accused Canelo of intentional doping. The relationship between the two boxers considerably soured as a result, making it impossible to hold joint press conferences before the fight.