

When Borodin died unexpectedly in 1887 he left his opera, Prince Igor, in a complete mess. It took the combined talents of Rimsky-Korsakov (as ever!) and Alexandr Glazunov to shape all the drafts, sketches and sundry bits of paper into anything resembling a complete opera.
But this very shaping, in some ways, also contributed to the problematic nature of the work. The two editors/compilers – distinguished composers themselves – were constrained inevitably to make decisions that, equally inevitably, have since been questioned. Below you’ll find a performance of one result of that questioning process, the so-called Mariinsky Edition, whose main (but far from only) deviation from the Korsakov/Glazunov score consists in reversing acts one and two, so that after the Prologue the action moves immediately to the Polovtsian camp.
This Kirov performance has been restricted to YouTube so I’m not allowed to embed it. But, don’t worry, the links for each section will take you there safely:

Prince Igor:
Overture
Prologue – The cathedral square in the ancient Russian city of Putivl
Act 1 – Evening in the Polovtsians’ camp
Act 2: Scene 1– The prince court of Vladimir Galitsky in Putivl
Act 2, scene 2 – A room in Yaroslavna’s palace
Act 3 – The Polovtsian camp
Act 4 – The city wall in the ruins of Putivl at dawn
I’m afraid this vocal score is of only limited use for following the above performance since a) there’s no English translation; b) it’s the original version which means that the acts are in the wrong order; and c) the Mariinsky Edition has some extra music. But, if you’re prepared to do a little juggling or are just interested in having sight of it…
Vocal score (Russian, German,
French)