I am writing a short story, and the boxing match which comes after 2/3 of the story is likely to exceed the length of the entire story, so how do you cut the action short? Do you describe the match from beginning to end, or do you somehow describe the last 2 minutes, which is a lot more manageable? Do you really have to cut to the last 2 minutes or so?
You don't have to skip to the end. Just don't get repetitive. Skip over uneventful periods of time. Look for (I mean make up) the events, the things that have meaning in the course of the fight, in every round if you can make up that many different but meaningful events. Different, because, don't repeat, it can be boring. One exception might be noticing a repeated pattern in your opponent's behavior that might be exploited, e.g. every time he jabs with his left, he drops his right guard. Or you spot a "tell", so you know when the left jab is coming and can land a counter blow.
What you want to do is focus on (and guide the reader through) the meaning, not just the mechanics of the fight. When I describe battles I describe what my character is thinking, and feeling, what is in their mind as they progress through the session, their inspirations and realizations, why they do what they do. Even if they are destined to prevail, I also make them less-than-perfect at the task, making errors, getting cut or hit, but soldiering on.
I don't know much about boxing, but an example:
They tested each other, jabs and blocks. Henry feinted and landed a good blow on Mike's ribs, but the follow-up, a hook to Mike's jaw, caught air as Mike astutely pulled his head back. A stupid mistake, Mike thought, but gone from his mind in a moment, that's what coach says, dwell on the past, you'll die in the present.
The judges scored no other points for the first three rounds. The audience grew restless, cat-calling. To them, nothing seemed to be happening, but Mike felt Henry tiring, he'd lost a tick, as the coach said. Now was the time to pay attention, don't lose a tick, watch for that dropped guard, keep your eyes on the prize. Be patient, take your hits, that pretty boy bitch will make a mistake.
Fifth round bell. Still nothing. Mike sat on the stool, tasting blood in his mouth, a cut inside his cheek. Coach jabbers in the corner, massaging his sore shoulders, his voice washed over Mike like a comforting hard shower. He did not process a word that was said. Sixth round, a minute in, then the pretty boy made a mistake. His first mistake.
Do the particular details of the boxing match matter to the story? What details matter? Why do they matter? Surely not every single punch and block is of utmost importance?
If I were describing a fencing match (something I understand far better than boxing, so you will forgive me if I focus on that), I would first ask myself what I want to showcase. It might be that I am showing my character in a fighting situation for the first time. If so, I need to show how they fight. Or it might be the fifth duel in the course of the novel, and it is only the interaction with the particular opponent is important. Or it might be that the particular fight is not important at all, only the fact of it having happened.
If I need to show how my character fights, I would spend some time describing his style, also maybe his mood. A loose translation of d'Artagnan's first duel in The Three Musketeers:
he fought like an enraged tiger, circling six times around his opponent, changing twenty times his guard and his terrain. (Alexandre Dumas, The Three Musketeers, chapter 5)
If someone has a copy of the book in English and can provide the actual quote, I would very much appreciate it.
My description would imply that some short time passes by in fighting, but I do not describe every parade and riposte. The only exchange I would describe in slow motion, as it where, is the one that produces some tangible result (disarming, wounding or killing the opponent). That exchange is the only important one.
If the part that's important about the fight is the interaction with the opponent, I might focus on the banter rather than on what each does with their sword.
Finally, if the particular's of the battle are not important, I might describe the preliminaries, the conversation before the battle starts, and then skip to "Alpha lay dead, Bravo's sword having pierced his throat".
A blow-by-blow breakdown of a fight is not very interesting to read. There is no story in it. A match, or a duel, or any kind of fight, should read like a story. The particular attacks and defences don't matter - it's the "feel" of the fight that does. What you want to catch is the action, the excitement, (or the fear,) the challenge.
Look at your boxing match as an emotional journey. Give it beats, and match them to changing emotions. Only describe what you need to evoke those emotions - nothing that would dilute them.