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.
You can look to the manga Hajime no Ippo for a case study on the subject... it is basically all about boxing matches which are described in great detail. Focus on the characters, and understand that boxing is not just two men (or women) punching each other. Every punch that you throw is an opening for your opponent, and it drains your energy a little bit more. Are they experienced boxers? Most amateur boxers are surprised at first by how much faster they run out of energy in a real fight compared to when they were training.
Boxing is a game of chess, where you need to think one step ahead of your opponent. The only difference is that there are no turns. You can throw or block as many punches as you are physically capable of, but each punch is harder to throw than the last.
It should be obvious that punches are being thrown in the boxing match. so to that effect, avoid: he threw a left hook. I swayed back and came back with a swift straight to the body, catching him off balance so I could finish him with an uppercut.
try not even describing the punches so much, because fiction is at its core all about the characters:
This guy has me beat at every angle. I know that for every punch I throw I'm going to take two in return. He's bigger than me... so how can he move so quick? He steps forward and all of the sudden I'm on the ground. The referee asks my if I can still fight--I guess I managed to haul myself onto my feet. I don't remember that. Stop the fight I think, but on reflex I earnestly lock eyes with him and smile, trying not to let on that I have a concussion, and say "Good to go, sir."
The ref nods gravely, and the round picks up again right away. While my opponent rushes in to overwhelm me, I'm still looking the ref in the eyes. No... Why? I think to myself. I squint my eyes shut as I prepare for the blow that that will finally retire me for good, and I picture the disappointment and pity on the faces of my friends and family ringside.
My trainer is yelling at me from the corner "On him!"
I ease my eyes cautiously open, and I see my opponents sweat as steam, condensing quickly in the cold stadium air. I see blood trickling down his face from the cut on his eye I gave him in the fifth round. I must have opened it further. He thrusts a veined, enormous arm directly at my face, and I'm too tired to react in time. It connects and I feel--nothing.
There's no power behind it. I can see my girlfriend through the bottom ropes. She's jumping up and down with the most excited smile I've ever seen her face. "You got him baby! One more shot!" She screams, her white-knuckled fists pumping back and forth. The loose-fitting ring on her finger catches the light.
I've got to get that resized for her before it falls right off, I think. Suddenly that becomes my priority, and I move towards her. But there's a man in the way. I try to stumble past him towards Karen, but he grabs hold of me, as if for support.
"Get off of me," I scream, and thrust my shoulder against his chest. He looks either confused or terrified, and he makes to clinch again. He leans forward to grab me, and I swing clumsily forward. I'm so surprised by how easily his head snaps back under my fist that I stumble forward, only managing to stay upright by supporting myself on the ropes.
Looking down over the ropes at my girlfriend, I'll never forget her smile in the instant between when she saw that I won, and when she realized that her face was spattered with blood.
The medical team had already taken out my opponent's mouth guard, and starting stuffing cotton against his nose to stem the bleeding........
etc. etc... So, set up the circumstances surrounding the fight, and set the final scene of the fight for the protagonist to deliver (or receive) the finishing blow, the climax of the scene--that one punch--in detail. That's my take on it, as a boxer, avid reader, and someone who claims to like writing but rarely does. Haha! Hope that helps, I had fun writing this reply.