O adversário venceu o jogador.

They are doing two different jobs, even though they look the same.

• The first O is the definite article the before adversário.
• The second o is also the definite article the before jogador.

So the structure is:

• O adversário = the opponent
• venceu = defeated / beat / won against
• o jogador = the player

In Portuguese, articles are used more often than in English, so it is very normal to see both nouns with o.

Adversário usually means opponent or rival, especially in sports, games, debates, or competitions.

It is not exactly the same as inimigo:

• adversário = opponent, someone on the other side in a contest
• inimigo = enemy, someone hostile in a stronger or more personal sense

So in this sentence, adversário sounds natural if we are talking about a match, competition, or contest.

Venceu is the third-person singular preterite form of the verb vencer.

• infinitive: vencer = to defeat, to beat, to overcome, to win
• ele/ela/você venceu = he/she/you defeated, beat, won

In this sentence, the subject is O adversário, which is third-person singular, so venceu matches it.

This tense refers to a completed action in the past:

• O adversário venceu o jogador. = The opponent defeated the player.

Yes. That is one reason learners often ask about it.

Depending on context, vencer can mean:

• to win
• to defeat / beat
• to overcome

Examples:

• Ela venceu a corrida. = She won the race.
• Ele venceu o adversário. = He beat the opponent.
• Nós vencemos o medo. = We overcame fear.

In your sentence, because the verb is followed by a person (o jogador), the meaning is defeated / beat.

Because o jogador is the direct object of venceu.

In Portuguese, vencer alguém means to defeat someone, with no preposition.

So:

• venceu o jogador = defeated the player

This is different from some Portuguese verbs that do require a preposition, such as:

• gostar de alguém/algo = to like someone/something
• precisar de algo = to need something

But vencer takes a direct object directly.

Portuguese word order helps you here.

In O adversário venceu o jogador:

• O adversário is the subject
• venceu is the verb
• o jogador is the object

So the natural reading is:

• the opponent defeated the player

If you switch the nouns, the meaning changes:

• O jogador venceu o adversário. = The player defeated the opponent.

Because both nouns are masculine singular and both have o, learners sometimes hesitate, but standard word order makes the roles clear.

Usually, no—not in normal standard Portuguese.

Portuguese generally prefers articles in a sentence like this:

• O adversário venceu o jogador.

If you remove them, it sounds unnatural in most ordinary contexts. You might occasionally see article omission in headlines, notes, labels, or very compressed styles, but not as the normal full sentence a learner should imitate.

Both adversário and jogador are masculine singular nouns here, so they take o.

Feminine versions would be:

• a adversária = the female opponent
• a jogadora = the female player

So possible variations are:

• A adversária venceu a jogadora.
• A adversária venceu o jogador.
• O adversário venceu a jogadora.

The article and noun ending often change together to match gender.

A Brazil Portuguese pronunciation guide would be roughly:

• adversário ≈ ahd-vehr-SAH-ryoo
• venceu ≈ ven-SEU
• jogador ≈ zho-gah-DOR in many Brazilian accents

About the accent mark in adversário:

• The á shows the stressed syllable: sá
• So the stress is ad-ver-SÁ-rio

Without learning every pronunciation rule yet, it is enough to remember that the word is stressed on sá.

It most commonly means player, especially in sports or games.

But depending on context, it can also refer to:

• a game player
• a gambler
• sometimes even a playboy / womanizer type meaning in certain contexts, though that is more contextual and less neutral

In a straightforward sentence like this one, jogador is most naturally understood as player.

Yes, that is a possible natural English rendering, although defeated or beat is usually the cleanest translation.

Portuguese vencer alguém often maps most directly to:

• beat someone
• defeat someone

English win against someone is understandable, but less direct and less common than beat in everyday speech.

So the best natural equivalents are:

• The opponent defeated the player.
• The opponent beat the player.

Yes, it is a normal and correct sentence.

That said, depending on context, a Brazilian might also use other verbs such as:

• ganhar de = to beat, to win against
  
  • O adversário ganhou do jogador.
• derrotar = to defeat
  
  • O adversário derrotou o jogador.

Your sentence with venceu is perfectly natural and slightly more formal or neutral than some everyday alternatives, but still very common.

It can, but the meaning becomes less clear.

Portuguese often allows a dropped subject when the context already tells you who it is. However, in this sentence:

• Venceu o jogador

this could sound ambiguous or incomplete without context. A listener may wonder:

• Who defeated the player?
• or, in some contexts, could o jogador be the subject after the verb?

So for clarity, especially for learners, keeping the explicit subject is best:

• O adversário venceu o jogador.