You may not have heard of Mexico’s Jose Luis Castillo. A lot of boxing purists think he beat Mayweather in a hard-fought contest back in 2002, when Mayweather was only 25. How did Castillo (almost) do it? He told Sports on Earth: “He also had very good speed and quickness but I just kept putting pressure on him as much as I could.”

In UFC, where the rounds are longer and there is more forms of attack to worry about, McGregor is still a relatively high-pressure fighter. If he can transfer that to the boxing ring, he might give Mayweather trouble in the early rounds.

Do the gloves make a difference?

Both fighters agreed to fight in 8-oz gloves, rather than the 10-oz gloves that are more usual in boxing at this weight. McGregor is a hard puncher and smaller gloves offer less protection to the fighter who gets hit, so this helps make the match that much spicier. The first few hard shots from McGregor will be crucial.

(McGregor’s Irish fans are certainly betting on him bringing the power. They have cut the forced the odds of a knockout victory for their man in the first five rounds from 33 to 1 all the way down 16 to 1.)

Look at Mayweather’s reaction. Did McGregor’s big shots hurt at all? Is he bothered by them? And most importantly, did any get through? McGregor has never faced someone like this before. Mayweather has one of the best defenses in the history of the sport. Ricky Hatton, the British boxer who was undefeated and a big hitter when the two met in 2007, recounts the fight:

I couldn’t have hit him with a handful of confetti and even when I got a shot through it half-caught his shoulder or he half-rolled it or he moved half a step back or half-slipped out of the way.

His timing was incredible. If I had him on the ropes and threw seven or eight punches, he blocked about six of them and then hit me with a haymaker.

If McGregor can’t translate his power to boxing gloves and can’t land a punch, this will be—as the critics say it will be—a very boring ass-whupping.

Does Floyd still have it?

Mayweather is 40. He hasn’t fought in two years. He’s a multi-millionaire. All of Mayweather’s skills—his timing, his footwork, his head movement—haven’t been tested in a few years. The first rounds are where the Irishman might take advantage. “Everyone expects Mayweather to win,” retired British boxer Carl Froch told the BBC. ”But McGregor is 29. He is young, fit, hungry and confident…Mayweather could just come unstuck early on and might get caught with something. That’s the big concern. It’s a fascinating match.”

But, then, McGregor is not used to boxing. It is a lot of work on the upper back, arms, and shoulders just to keep your hands up for 12 rounds. And that is before you worry about someone trying to take your head off.

Look to see how hard McGregor works in the first three rounds—he might going for the knockout as he has promised, in the hopes of avoiding a long fight. Or he might be thinking smarter than he acts, and trying to save himself a bit.

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