All you have to do is check out the odds for Saturday’s showdown to confirm the biggest fight of 2018 is a toss up.

Oddsmakers installed Gennady “GGG” Golovkin as a slight favorite (-160) over Saul “Canelo” Alvarez (+140) once the two fighters finalized the terms of their highly-anticipated rematch (HBO PPV, 8 pm ET). Bettors saw similar odds for the first fight last year. While it’s tough to expect any big surprises from two fighters who were sparring partners back in the day, ask the right people ahead of the mega match and they’ll tell you something has to change.

Even though we all expect GGG (38-0-1, 34 KOs) to be his usual relentless self, the epitome of “Mexican style” boxing, and Canelo (49-1-2, 34 KOs) will demonstrate yet again that he’s one of the premier counter punchers, the veterans must add a wrinkle or two. Becoming the undisputed top middleweight of the world demands it this time around.

“Both of them have to do something different than the first fight,” says boxing legend Bernard Hopkins.

Andre Ward, another recently retired legend in the ring, agrees.

“That’s what rematches are all about,” he says. “If you had a guy that won by four rounds, six rounds, that guy really doesn’t need to make any adjustments. But that’s not the case here.”

“If you had a guy that won by four rounds, six rounds [in the first fight], that guy really doesn’t need to make any adjustments. But that’s not the case here.”

Last year’s bout was a war, even though it ended in a controversial draw thanks to one of the most egregious scorecards in boxing history. As we wrote earlier this week, the pettiness between both fighters and their camps escalated to epic levels, making the prospects for fireworks at T-Mobile Arena in Las Vegas highly likely. “It’s legitimate, combative venom back and forth,” says Hopkins.

The future Hall of Famer, who fought until he was 51, hasn’t seen this much sniping between boxers in nearly 17 years since Hopkins disrespected the Puerto Rican flag ahead of his bout with Felix Trinidad. And the bad blood flowing before a fight can often affect what we see in the ring. Will Canelo’s desire for revenge—to defend his name that’s been dragged in the dirt by GGG and his camp following Canelo’s positive test for performance-enhancing drugs earlier this year—cloud his judgment?

“If the dislike starts to get the best of them then they’ll find themselves fighting in ways they shouldn’t fight. It favors Golovkin,” says Ward. “Golovkin needs a toe-to-toe battle to be successful. The anger and frustration is going to benefit him more. The burden is more on Canelo to channel those emotions more than on Golovkin.”

The biggest question facing GGG, the WBA, IBO, and WBC champion, just might be whether or not age finally catches up with him. He’s 36, and at some point Father Time will get the best of him. Is this fight finally it? Only the really big boys, aka the heavyweights, usually have the juice well into their late 30s and early 40s. There are exceptions to the rule. Hopkins certainly was.

“To me, it’s easy to see a guy slow down, to know the signs of a step back or two,” says Hopkins.

While Hopkins wouldn’t definitively say if he has seen a deterioration of GGG’s skills, he wonders if Golovkin, who can break Hopkins’ record of 20 straight middleweight title defenses Saturday, has it in him to be unpredictable for once.

“The big question to me is, in my 28 years as a professional, can GGG adjust when we’ve never seen him adjust before and do something we’ve never seen him do before?” says Hopkins. “If he can answer that question, then Canleo’s in trouble.”

Hopkins, of course, is far from a neutral observer. He’s part of Golden Boy Promotions, Canelo’s promoter, and he will be rooting heavily for Canelo. A victory is good for business, but so is an even better performance than the one the Mexican pugilist provided fans last September when some—including GGG’s outspoken trainer Abel Sanchez—accused Canelo of running around the ring.

Ward, on the other hand, is a neutral observer. The former undisputed light heavyweight champion of the world retired from the game last year and now does broadcasting work for ESPN, HBO, and hosts “The Contender” on EPIX. He also agrees that Golovkin might be an old dog who can’t learn a new trick.

“Everybody wants to see who is going to make the necessary adjustments and Canelo has the upside in that department,” says Ward. “I feel like his bag is a lot deeper than Golovkin’s. I don’t know how many adjustments Golovkin can actually make at this stage in his career and at his age.”

As for predictions, it’s no surprise who Hopkins sees winning.

“Canelo wins a unanimous decision that won’t be a surprise to most,” he says. “Some will be scratching their heads how un-difficult it was. No controversy, No debate. A lot of people wondering did he figure him out the first time? I’ll give you the answer now: Yes. Rock solid decision, Canelo.”

Ward also thinks it’s the underdog’s fight to lose.

“At the end of the day we don’t know who is going to channel all of the emotions, all of the dislike, the pressure, the pressure of the moment, and who’s going to go out there and execute,” he says. “I will always lean toward the fighter who can do more. When I analyze two fighters, I always look at who has more tricks in their bag? And that’s Canelo.”