The monster, in a single whirlwind, rushed up the bank and made straight for the Tang Monk.

一個旋風, 'one whirlwind,' is how he travels. 徑搶唐僧: straight for the Tang Monk. Note who he goes for — not the two armed disciples but the soft, edible man in the middle. Demons in this book have their priorities.

In alarm the Pilgrim caught the master up in his arms, hurried him to high ground, and turning, got him clear.

慌得, 'so alarmed that' (得 de) — and the monkey's body moves before his temper does. He takes the master up (抱住), runs him to high ground (急登高岸), and leaves the fighting to somebody else. Worth noticing how well he behaves in this first instant, because it does not last.

That Bajie set down the luggage, whipped out his muckrake, and struck at the monster with a downward thrust.

Bajie puts down the 擔子 — the carrying-pole and baggage that are his standing job — and gets out the 釘鈀, the nine-toothed rake. The verb is the interesting part: 築 is not 'strike' but 'tamp down,' the word for ramming earth into a wall. It is a farming motion, and it is the only way he ever swings the thing.

The monster brought up his precious staff to parry, and the two of them, on the bank of the Flowing Sands, each displayed his prowess. It was a fine fight:

架住, 'blocked it.' Then 各逞英雄, 'each showing off his heroism,' and the tag 這一場好鬥 — 'now that was a fight.' In this novel the phrase is a stage direction: prose stops here, verse begins, and the brawl gets the full formal treatment.

The nine-toothed rake, the demon-quelling staff — the two closed as foes upon the river's bank.

The rhapsody opens by putting the two weapons in the ring before the two men. 降妖杖 is the 'demon-quelling staff' — 降 here is xiáng, 'to subdue,' not jiàng, 'to descend.' 相敵, 'matched as enemies' (相 xiāng, mutually).

This one, the grand Marshal Tianpeng who once held all command; that one, the Curtain-Raising General, cast down from grace.

Here is the joke the whole rhapsody is built on. 總督大天蓬 is Bajie's old job: 天蓬元帥, Marshal Tianpeng, who commanded the Heavenly River. 謫下捲簾將 is the monster's: 捲簾大將, the Curtain-Raising General (將 is jiàng, a rank), the officer who lifted the curtain in front of the Jade Emperor's throne — a ceremonial post, and a very senior one, precisely because it put him nearest the throne. Two sacked officials, brawling in a river.

In years gone by they had met in the Hall of Divine Mists; today they grappled, staking all their fierce brute force.

靈霄 is the 靈霄寶殿, the Jade Emperor's throne-hall. These two used to stand in the same room. Neither knows the other now, and the verse takes its time enjoying that.

This one's rake struck out like a dragon baring its claws; that one's staff parried like a tusk-grinding elephant.

探爪龍, a dragon reaching out a claw, for the rake going in; 磨牙象, an elephant grinding its tusks, for the staff coming across to block. Attack and guard, each given a beast.

Now spread wide in the Great Four-Square guard; now boring in against the very thrust of the wind.

大四平 and 迎風戧 are named stances out of the real martial repertoire — roughly the 'Great Four-Square' and the 'Ward Into the Wind.' A Ming reader knew these the way a reader now knows a named finishing move, and dropping them in gives the exchange the texture of an actual bout rather than a scuffle.

This one clawed with never a thought for head or face; that one loosed his blows with never a wasted swing.

沒頭沒臉 is still what Chinese reaches for when somebody goes at a thing in a blind flurry, with no thought for where the blows land. Against it, 無亂無空放: not a wild swing, not a wasted one. The couplet is a pair of character sketches disguised as choreography — Bajie all appetite, the monster all discipline.

The one, a man-devouring fiend long lord of the Flowing Sands; the other, a general keeping the faith and holding to his vows.

The last couplet drops the choreography and states the moral score. 久占流沙界吃人精: a man-eating spirit who has held this river a long time (占 is zhàn, to occupy). 秉教迦持修行將: a general who took the vows and keeps them (將 jiàng), where 迦持 transliterates a Sanskrit term for religious observance. Man-eater against convert — which is exactly the line the monster himself is going to be carried across before the chapter ends.

The two of them went back and forth, and having fought some twenty rounds, neither could gain the upper hand.

二十回合, twenty rounds, and 不分勝負 — nothing to choose between them (分 is fēn, to divide, hence to decide). In this book a dead heat means one thing: somebody is about to interfere.