LAS VEGAS — In the four years since Gennadiy Golovkin last fought Canelo Alvarez at T-Mobile Arena, much has changed. Alvarez rode a victory over Golovkin in that second fight to even greater heights.

Alvarez won a light heavyweight title, became the undisputed super middleweight champion and was widely regarded as the No. 1 pound-for-pound fighter in boxing. On Saturday, when they meet again at T-Mobile Arena in their trilogy bout, this time for the undisputed super middleweight championship, Alvarez is a whopping -500 favorite at BetMGM.

The majority of media who covered the first two bouts saw them as victories for Golovkin. On Sept. 16, 2017, their first fight was a split draw, handing Golovkin the first blemish on his record after 37 consecutive victories to begin his career. Adalaide Byrd had a ridiculously incorrect card of 10-2 for Alvarez. Don Trella scored it a draw — not an unreasonable verdict — but he gave the seventh, Golovkin’s best round in the fight, to Alvarez. That meant that instead of Golovkin winning a split decision, the fight was a split draw.

The rematch was on Sept. 15, 2018, and Alvarez won a majority decision. Six scorecards were turned in after those two fights. Alvarez had the edge on three, two were draws and Golovkin had the edge on one.

The verdicts in each of those fights has been much debated, though if a fighter doesn’t want to be at the mercy of the judging, they have to finish the fight.

History, though, would be vastly different if Golovkin had gotten those two victories. He’d be heading into Saturday’s trilogy bout with a 44-0 record and a chance to match Floyd Mayweather’s 50-0 mark.

And at 44-0 with 37 knockouts, he’d be in the conversation, at least, as the greatest middleweight of all time.

As it is, he goes into Saturday’s fight regarded as the best middleweight of his era, but not really in the discussion for top-five middleweight of all time. And he’s no longer regarded as one of the pound-for-pound best in the world.

Some of that is due to his age. At 40, he’s not as quick and as explosive as he’d been. But neither was Mayweather as quick or as explosive as he’d once been when he reeled off the final six or eight victories in his illustrious career.

There’s also a bitterness that has stuck inside Golovkin. He’s had to play a secondary role to Alvarez since their second fight, which he also deeply believes he won. And he’s not so crazy about where he is promotionally at this stage.

Yahoo Sports asked him about a comment his trainer Johnathon Banks made to Ring magazine about the fight being brutal. Golovkin turned it into a shot at promoter Eddie Hearn even though Hearn’s name had not come up in the conversation to that point.

“Johnathon can hype things up better than many promoters, including Eddie Hearn,” he said. “I’m also certain this is going to be a very interesting fight with a lot of tension.”

Golovkin, who enters the bout as a unified middleweight champion, badly needs a win on Saturday or he’ll just about be to the end of the line. Oh, he clearly can still fight, but if he loses to Alvarez yet again, there’s not going to be a lot of truly significant fights waiting for him.

He’s 40 years old now and has been at or near the top of his sport for more than a decade. His two fights with Alvarez combined to sell 2.4 million pay-per-views in the U.S. on HBO Sports and they had a combined gate of over $51 million. They were the third- and fourth-highest boxing gates in Nevada history.

Saturday’s bout is still not a sell-out with, as they say, plenty of good seats still remaining. The fight is on pay-per-view on both DAZN and PPV.com, but it’s not expected to come close to the performance of either of the first two.

It’s not clear why that is. Golovkin was asked if fighting in such a high-pressure atmosphere in those first two bouts with Alvarez with the world watching helped him better compete under pressure. He turned that into a shot at DAZN, and that makes one wonder where his head is at heading into the trilogy.

“Being a big fan of boxing, I have high hopes that this fight is an opportunity to bring boxing back to the high level it deserves,” Golovkin said. “Those first [two] fights were on HBO and they were different times with a different approach. When HBO decided not to continue supporting that, new companies appeared with a different vision.

“They made a number of mistakes and I hope this fight is an opportunity to bring boxing back to the heights it deserves.”

The first 24 rounds they spent together were some of the best in boxing in those two years, so there is no reason why the third fight can’t be the same.

Alvarez, of course, will be fighting with a bit of additional urgency since he is coming off a loss in a light heavyweight title bout to Dmitriy Bivol.

Golovkin, though, is the one with the most to fight for and the most to gain from a win. The judging in those first two fights may have kept him from approaching all-time great status and changed the course of his career, but there is no changing it now.

Golovkin needs the performance of a lifetime to remind people of the monster he once was.