"My corner told me I needed to win the final round and that's what I did".
Mexican star Alvarez produced a performance of guts and resilience to inflict the first defeat of Golovkin's career with a majority decision at the T-Mobile Arena.
Lemieux lands a left hook with two minutes and 44 seconds remaining of the first round and O'Sullivan struggles to stand.
Two judges favoured Alvarez 115-113, while a third had it 114-114. Scores were 114-114, 115-113, 115-113 for Canelo.
Golovkin, the big puncher from Kazakhstan, has gone the distance twice in his last three fights, including the draw with Alvarez. This time it was Golovkin who was upset, and he stormed out of the ring without talking. He's a great fighter but in the end I got the victory. The judges are good judges and it was a good fight. Golovkin landed the more dramatic punches late, trying to create some separation and erase any doubt the judges might have had, but Alvarez had been tactical and earned his points all along the way.
"It was very hard and [Golovkin] is a great fighter". "I had hit close going into the 12th round".
A great boxing fight was just ruined by a bogus decision by the judges ... again.
Nearly immediately there was talk of a third fight between two middleweights who now know each other well. But for right now, I will enjoy time with my family. "No third fight for at least a year guys (long rest)".
Atlas added that he felt Golovkin was controlling the fight and deserved to win.
"We had a great fight, the one we expected the first time around".
"Some very close rounds that could have went either way".
However, as the bout transpired, the two fighters were neck and neck.
Then, the original date for the rematch - May 5 - was scuttled after Alvarez twice tested positive for a banned substance, clenbuterol, during training and was hit with a six-month suspension from the Nevada State Athletic Commission. While the fight itself was a masterpiece, the controversy surrounding the resulting split draw and puzzling 118-110 nod for Canelo left a dark cloud over an otherwise stellar showing from both men.
The stakes are high as whoever wins will have a crack at taking on the victor of the main fight.
He said: "I want to damage him, for life". He was the one who was backing up. "It was a clear victory".
Alvarez said in the days leading to the fight that he went to bed every night visualising a knockout.