Learn Hardcore Indonesian: Pertandingan besok malam ditunda karena hujan deras. - The match tomorrow night is postponed because of heavy rain.

Ditunda means "postponed" in the passive voice. Root: tunda (postpone); prefix di- marks passive.
It’s used because the subject (Pertandingan besok malam) is the thing affected by the action.
Active counterpart: Panitia menunda pertandingan besok malam. (The committee postponed tomorrow night’s match.)

Where is the verb "to be" (is/was) in Indonesian?

Indonesian doesn’t use a separate "to be" in passive constructions like this. The verb form ditunda already conveys "is/was postponed." You don’t add adalah here; adalah is used for equational sentences (X = Y), not for passive verbs.

What tense is this? How do I say "will be/has been postponed"?

Indonesian doesn’t mark tense on the verb. Time is shown by context words:

Neutral announcement: Pertandingan besok malam ditunda.
Has been (already): Pertandingan besok malam sudah/telah ditunda.
Will be: Pertandingan besok malam akan ditunda. Use sudah/telah (already) and akan (will) to clarify timing if needed.

Does besok malam modify the noun or the whole sentence?

Here it modifies the noun: Pertandingan [besok malam] = "tomorrow night’s match." It identifies which match is being talked about, not when the postponement happens.

Can I say malam besok instead of besok malam?

Both are understood and acceptable. Besok malam is more common and neutral. Malam besok appears too, but is slightly less common in many regions. You can also say:

Malam ini = tonight
Tadi malam = last night
Besok pagi / Pagi besok = tomorrow morning (both used; first is more common)

Do I need a preposition like pada before besok malam?

No. You normally don’t use pada before words like besok, kemarin, nanti, sekarang. Use pada with specific dates/days if you like:

Pertandingan pada hari Senin ditunda.
Pertandingan pada 12 Mei ditunda.

Can I put the time at the front, like Besok malam, pertandingan ditunda?

Avoid that here. Besok malam, pertandingan ditunda literally reads as "Tomorrow night, the match is postponed," which suggests the act of postponing happens tomorrow night. Because besok malam identifies the match, keep it with pertandingan. For emphasis on reason, front the reason instead:

Karena hujan deras, pertandingan besok malam ditunda.

How does karena work? Are there alternatives?

Karena means "because" and introduces a reason clause: … ditunda karena hujan deras.
Alternatives:
- Sebab = because (more formal/literary)
- Gara-gara = because/due to (informal; can imply blame/annoyance)
You may see dikarenakan in formal notices, but karena is usually clearer and leaner.

Is hujan deras the only way to say "heavy rain"?

Hujan deras and hujan lebat both mean "heavy rain."
Deras is an adjective describing strong flow/volume (water, rain): arus deras (swift current).
Don’t say deras hujan; adjectives follow the noun.

If I want to mention the agent ("by the committee"), how do I do that?

Add an optional oleh-phrase:

Pertandingan besok malam ditunda oleh panitia karena hujan deras. Leaving the agent out is very common, especially in announcements.

How do I say when it’s moved to?

Use phrases like:

… diundur ke hari Jumat. (moved back to Friday)
… ditunda sampai minggu depan. (postponed until next week)
… dijadwalkan ulang ke pukul 20.00. (rescheduled to 8 p.m.)

What’s the difference between ditunda, diundur, ditangguhkan, and dibatalkan?

Ditunda: postponed (general).
Diundur: moved to a later time/date (very common in everyday speech).
Ditangguhkan: suspended/put on hold (often formal, may be indefinite).
Dibatalkan: canceled (will not happen).

What exactly does pertandingan mean? How is it formed? Alternatives?

Pertandingan = a match/contest; noun from root tanding ("to compete"), with per-…-an nominalization.
Related forms: bertanding (to compete).
Alternatives:
- Laga (sports news/journalistic).
- Perlombaan (contest/race).
- Permainan (a game/play; more general, not necessarily a competitive match).
- Gim (a game, often in sports sets or video games).

Is the noun definite or plural? How would I show that?

Indonesian has no articles; pertandingan can be "the match" or "a match." Mark it if needed:

Definite: pertandingan itu (that/the match).
Plural (optional): pertandingan-pertandingan or a quantifier like beberapa pertandingan (several matches).
Specific group: para panitia (the committee members), etc.

Any quick pronunciation tips for the tricky parts?

Pertandingan: per-tan-ding-an; the ng is the velar nasal [ng] as in "sing."
Besok: commonly pronounced with a schwa-like first vowel: [bə-sok].
Deras: the first e is a schwa: [də-ras].
Karena: [ka-rə-na].
Stress is light and fairly even; don’t over-stress syllables as in English.