Trận đấu này không tệ.

In Vietnamese, demonstratives like này (this) usually come after the noun, not before it.

So:

• trận đấu này = this match
• literally: match this

This is a very common Vietnamese pattern:

• cuốn sách này = this book
• người này = this person
• cái bàn này = this table

So the word order here is completely normal for Vietnamese.

Trận đấu is a common noun phrase meaning match, game, or contest, especially in sports.

The two parts are:

• trận: a bout, match, round, or event of conflict/competition
• đấu: to fight, compete, or contest

Together, trận đấu works as a fixed expression for a match/game.

You will also hear shorter forms depending on context:

• trận này = this match
• cuộc đấu = contest/bout
• trận bóng = football/soccer match, depending on context

So in this sentence, trận đấu này is just a natural way to say this match.

Không is the basic Vietnamese word for not.

In this sentence, it negates the adjective tệ:

• tệ = bad / poor / terrible
• không tệ = not bad

A very common Vietnamese sentence pattern is:

• noun + không + adjective

For example:

• Phim này không hay. = This movie is not good.
• Món này không đắt. = This dish is not expensive.
• Trận đấu này không tệ. = This match is not bad.

So không works much like not in English.

It can do both, depending on tone and context.

Literally, không tệ means not bad. But just like in English, it often suggests something more positive than the literal words:

• neutral: not bad
• slightly positive: pretty good
• pleasantly surprised: actually quite good

So if someone says Trận đấu này không tệ, they may simply mean it was acceptable, or they may be softly praising it.

This kind of understatement is very natural in Vietnamese, just as it is in English.

Tệ means bad, poor, or awful, depending on context.

Its strength depends on how it is used:

• tệ = bad / poor
• rất tệ = very bad
• tệ quá = so bad / terrible

By itself, tệ is often stronger than just mildly disappointing. So không tệ can sound nicer than a direct positive adjective because it avoids making an overly strong claim.

For example:

• Bài này tệ. = This piece/work is bad.
• Bài này không tệ. = This piece/work is not bad.

So tệ is negative, and không tệ softens that into a mild positive or at least a non-negative judgment.

Yes, Trận đấu này không tệ is natural and correct.

In conversation, people might also say:

• Trận này không tệ. = This match isn’t bad.
• Cũng không tệ. = Also not bad / Not bad either.
• Trận đấu này khá hay. = This match is quite good.
• Trận này ổn đấy. = This match is okay / pretty decent.

So your sentence is good Vietnamese. It sounds fairly neutral and natural.

You can often use trận by itself when the context is clear.

For example:

• Trận này không tệ. = This match isn’t bad.

That works well if everyone already knows you are talking about a match or game.

However, trận has a broader range of meanings in Vietnamese. It can refer to things like:

• a battle
• a match
• a round
• even an occurrence of something like rain or illness in some contexts

So trận đấu is more specific and clearer, especially for learners.

In short:

• trận đấu này = clearer, more explicit
• trận này = shorter, very natural when context is obvious

The structure is:

• Trận đấu này = subject/topic noun phrase
• không tệ = predicate describing it

So the overall pattern is:

• [noun phrase] + [negative marker] + [adjective]

In other words:

• This match + not + bad

Vietnamese often uses adjectives directly as the predicate, without a separate word for is in simple present descriptions.

So unlike English:

• This match is not bad

Vietnamese simply says:

• Trận đấu này không tệ

There is no need for a verb meaning is here.

Because Vietnamese usually does not use a copula like English is when linking a noun to an adjective.

English says:

• The match is bad
• The match is not bad

Vietnamese says:

• Trận đấu tệ
• Trận đấu không tệ

This is normal. In descriptive sentences, adjectives can act like the predicate by themselves.

Vietnamese does have là, but it is mainly used to link nouns, not adjectives, in most basic cases.

For example:

• Anh ấy là giáo viên. = He is a teacher.

But with adjectives, you normally do not use là:

• Trận đấu này không tệ. not Trận đấu này là không tệ.

So the lack of is is a core feature of Vietnamese grammar.

A rough breakdown is:

• Trận: low, heavy, glottalized tone
• đấu: rising-broken tone
• này: level or slightly falling, depending on dialect
• không: level tone
• tệ: heavy glottalized tone

A rough English-style approximation is something like:

• chuhn dau nay khong teh

But that does not capture the tones accurately, and tones matter a lot in Vietnamese.

A few notes:

• tr in trận is not exactly English ch, though learners often approximate it that way at first.
• đ is like a normal English d.
• kh is like a breathy k sound, similar to the ch in German Bach or Scottish loch, though many learners start with a simple k-like approximation.
• The tones on trận and tệ are especially important.

If you are learning pronunciation, it is best to listen to native audio and repeat whole chunks:

• trận đấu này
• không tệ

Yes. If you want to sound more clearly positive, you could say:

• Trận đấu này hay. = This match is good / interesting.
• Trận đấu này khá hay. = This match is quite good.
• Trận đấu này ổn. = This match is okay / decent.
• Trận đấu này tuyệt. = This match is great.

Compared with these:

• không tệ is softer and more understated
• hay is more directly positive
• ổn is casual and moderate
• tuyệt is strongly positive

So không tệ is useful when you want to sound measured rather than enthusiastic.

No. They are related, but they are not used the same way.

• này usually comes after a noun:
  trận đấu này = this match
• đây often means here, or it can function as this in other sentence patterns

Compare:

• Trận đấu này không tệ. = This match isn’t bad.
• Đây là trận đấu hay. = This is a good match.
• Tôi ở đây. = I am here.

So in your sentence, này is the correct choice because it modifies trận đấu directly.