Mam nadzieję, że nasz zawodnik strzeli jutro pierwszą bramkę.

Because nadzieję is the accusative singular form of nadzieja.

In mam nadzieję, the verb mieć takes a direct object, so nadzieja changes case:

• nadzieja = nominative
• nadzieję = accusative

This whole expression, mam nadzieję, is the normal Polish way to say I hope.

Że means that and introduces the second clause.

So the structure is:

• Mam nadzieję = I hope
• że... = that...

Polish usually keeps że in sentences like this, even though English often omits that.

Because in Polish, a subordinate clause introduced by że is normally separated by a comma.

So:

• Mam nadzieję, że...

This is standard Polish punctuation. Even if English might sometimes feel lighter on commas, Polish is stricter here.

Polish often does not need a separate word for will.

Strzeli is from the perfective verb strzelić. Perfective verbs have a form that looks like the present tense, but it actually refers to the future.

So:

• strzeli = he/she will score

This is very common in Polish. With perfective verbs, the so-called present form usually has future meaning.

They come from two different aspects:

• strzelić → strzeli = perfective, one completed action
• strzelać → strzela = imperfective, ongoing/habitual action

In this sentence, strzeli is used because the speaker hopes for one completed result: scoring a goal.

Compare:

• strzela = shoots / is shooting / shoots regularly
• strzeli = will score / will shoot successfully once

So strzeli bramkę fits the idea of a single achieved goal.

Because nasz zawodnik is the subject of the clause że nasz zawodnik strzeli..., so it stays in the nominative case.

• nasz zawodnik = nominative, subject
• naszego zawodnika = accusative/genitive form, used in other roles

Here, the player is the one doing the action, so nominative is required.

Because this is the direct object of strzeli and it is a feminine singular noun phrase in the accusative.

Base form:

• pierwsza bramka = nominative

In the sentence:

• pierwszą bramkę = accusative

Both words change because adjectives must agree with the noun in:

• gender
• number
• case

So:

• pierwsza → pierwszą
• bramka → bramkę

Yes. In sports, bramka can refer to a goal.

It can mean either:

• the physical goal/net
• a scored goal

In this sentence, because of strzelić, it clearly means a scored goal.

You may also hear gol in similar contexts. Both are common, though gol is often the most direct equivalent of English goal.

Yes, the word order could change. Polish word order is fairly flexible.

This version:

• ...zawodnik strzeli jutro pierwszą bramkę

sounds natural and neutral.

Other possible orders include:

• ...że jutro nasz zawodnik strzeli pierwszą bramkę
• ...że nasz zawodnik jutro strzeli pierwszą bramkę

The meaning stays basically the same, but the emphasis shifts slightly. In Polish, word order often helps show what is being highlighted.

Not necessarily. Zawodnik is a general word for competitor, athlete, or player.

By itself, it does not specify the sport. The context here suggests a sport where you can score a goal, such as football, hockey, handball, and so on.

If you wanted to be more specific, you could use a sport-specific word, for example:

• piłkarz = footballer
• hokeista = hockey player

So zawodnik is broader and more neutral.