Trọng tài thấy cầu thủ phạm lỗi.

A natural word-by-word breakdown is:

• trọng tài = referee
• thấy = see / sees / saw
• cầu thủ = player
• phạm lỗi = commit a foul / break the rules / foul

So the structure is basically:

• Trọng tài = subject
• thấy = main verb
• cầu thủ phạm lỗi = what the referee sees

In other words, the sentence means that the referee sees that a player commits a foul, or sees a player committing a foul.

Vietnamese usually does not require articles like the and a/an the way English does.

So:

• trọng tài can mean the referee, a referee, or just referee depending on context
• cầu thủ can mean the player, a player, or players depending on context

If you want to be more specific, you can add words such as:

• một cầu thủ = a player
• các cầu thủ = the players / players
• trọng tài đó = that referee
• người trọng tài is possible in some contexts, but plain trọng tài is the normal form here

Vietnamese often leaves this kind of definiteness to context.

The basic order is:

• Subject + Verb + Object/Clause

Here that gives:

• Trọng tài = subject
• thấy = verb
• cầu thủ phạm lỗi = the thing being seen

So the sentence literally feels like:

• Referee sees player commit-foul

This is very normal Vietnamese word order. English often needs extra words like that or a, but Vietnamese can say it more directly.

Because thấy is the main verb of the sentence: to see.

What follows it is the content of what is seen:

• cầu thủ phạm lỗi = the player committing a foul / that the player committed a foul

This pattern is common in Vietnamese with perception verbs:

• thấy ai làm gì = see someone do something
• nghe ai nói gì = hear someone say something

So thấy cầu thủ phạm lỗi is a very natural structure meaning see the player commit a foul.

It is made of two parts:

• phạm = commit, violate
• lỗi = fault, mistake, offense, foul

Together, phạm lỗi means to commit a foul / to commit an offense / to break a rule.

In sports, this is a common way to say that a player fouls. So:

• cầu thủ phạm lỗi = the player commits a foul / the player fouls

Even though it is written as two separate syllables, it functions as one verbal idea.

It is best understood as a small clause:

• cầu thủ = subject of the small clause
• phạm lỗi = predicate

So after thấy, Vietnamese can put a mini subject-predicate unit:

• thấy cầu thủ phạm lỗi = see that the player fouls / see the player committing a foul

This is one reason the sentence feels compact in Vietnamese. English often has to choose between:

• The referee sees the player commit a foul
• The referee sees that the player committed a foul

Vietnamese can often cover both ideas with the same structure.

By itself, it can mean either, depending on context.

Vietnamese does not have mandatory tense marking like English. So thấy does not automatically tell you whether the action is present, past, or sometimes even habitual.

Context decides:

• in a live sports description: The referee sees the player commit a foul
• in a story about a match: The referee saw the player commit a foul

If you want to make the time clearer, you can add markers such as:

• đã thấy = saw
• đang thấy = is seeing, though this is less natural in many contexts
• no marker = often just neutral, with tense understood from context

Usually, plain cầu thủ in this sentence is most naturally understood as a player or the player, singular.

If you clearly want plural, Vietnamese often adds something like:

• các cầu thủ = players / the players
• nhiều cầu thủ = many players

So:

• Trọng tài thấy các cầu thủ phạm lỗi = The referee sees the players committing fouls

Without các or another plural marker, singular is the more likely reading here.

This is normal in Vietnamese. Many everyday nouns are made of two syllables and are written with a space between syllables:

• trọng tài = referee
• cầu thủ = player
• bóng đá = football / soccer

So even though English learners may feel it looks like two separate words, it functions as one lexical item.

You should think of trọng tài as a fixed compound noun meaning referee.

In this sentence, yes, the most natural meaning is literal seeing or noticing with one’s eyes.

Depending on context, thấy can sometimes extend to meanings like:

• feel
• find
• notice
• think something seems a certain way

But in a sports sentence with trọng tài and phạm lỗi, the reading is straightforward:

• the referee sees/notices the foul

So here, thấy is best understood as see or notice.

Yes. Vietnamese often allows that kind of flexibility.

Trọng tài thấy cầu thủ phạm lỗi can be understood as:

• The referee sees the player commit a foul
• The referee sees that the player committed a foul
• The referee notices that the player has fouled

English forces you to choose a more specific structure, but Vietnamese often leaves that distinction less explicit.

The exact nuance comes from context:

• direct real-time observation
• recognition of an offense
• reporting what happened in a match

You can add markers or extra words depending on what you want to emphasize.

Examples:

• Trọng tài đã thấy cầu thủ phạm lỗi.
  = The referee saw the player commit a foul.

• Trọng tài thấy một cầu thủ phạm lỗi.
  = The referee sees/saw a player commit a foul.

• Trọng tài thấy cầu thủ đó phạm lỗi.
  = The referee sees/saw that player commit a foul.

• Trọng tài phát hiện cầu thủ phạm lỗi.
  = The referee detects/notices that the player committed a foul.

So the original sentence is grammatical and natural, but Vietnamese can always add more detail if needed.

A rough guide:

• Trọng: heavy falling tone
• tài: rising tone
• thấy: rising/broken tone
• cầu: falling tone
• thủ: falling-rising tone
• phạm: heavy falling tone
• lỗi: broken/rising tone

A learner-friendly way to practice is to chunk it like this:

• Trọng tài / thấy / cầu thủ / phạm lỗi

Try to learn each two-syllable unit as a chunk:

• trọng tài
• cầu thủ
• phạm lỗi

That is often easier than building the sentence one syllable at a time.