Если судья назначит пенальти, вратарь должен быть особенно внимательным.

In Russian, a perfective verb in the present-looking form usually expresses the future.

So:

• назначить = perfective, to assign / award / call (as a completed action)
• назначит = he/she will award

After если (if), Russian often uses this form when talking about a future possible event:

• Если судья назначит пенальти... = If the referee awards a penalty...

English uses if + present (if the referee awards), while Russian often uses если + perfective future for a one-time completed event.

Because the sentence refers to a single completed action: the referee either does award the penalty or doesn't.

Perfective verbs are used when the action is seen as:

• completed,
• one-time,
• reaching a result.

Here the important point is the result: the penalty is awarded.

Compare:

• Если судья назначит пенальти... = if the referee awards the penalty (one concrete event)
• Если судья назначает пенальти... would sound more like a habitual or descriptive situation, not this specific future case.

Literally, назначить often means to appoint, to assign, or to schedule, depending on context. But in sports language, назначить пенальти means:

• to award a penalty
• to give a penalty

So this is a set expression used in football/soccer.

Other examples of назначить in different contexts:

• назначить встречу = to arrange/schedule a meeting
• назначить врача = to appoint a doctor
• назначить штраф = to impose a fine

The core idea is officially assigning something.

Пенальти is an indeclinable noun in Russian. That means it usually keeps the same form in all cases.

So you get:

• пенальти
• без пенальти
• к пенальти
• назначить пенальти

The case is still determined by grammar, but the word itself does not change form.

This is common with some borrowed words in Russian.

Because Если судья назначит пенальти is a subordinate clause introduced by если (if), and Russian normally separates such clauses with a comma.

So the structure is:

• Если ... , ...
• If ..., ...

This comma is standard in Russian, even when English might feel slightly less strict about punctuation.

Because должен means must / should / is supposed to, but it usually needs either:

1. an infinitive verb, or
2. a clearly understood predicate from context.

Here the idea is:

• the goalkeeper must be especially attentive

So Russian says:

• вратарь должен быть особенно внимательным

Without быть, the sentence would feel incomplete here, because внимательным is a state/quality, not an action verb.

Compare:

• Он должен прийти. = He must come.
• Он должен быть внимательным. = He must be attentive.

Because after быть in this kind of structure, Russian often uses the instrumental case for the predicate noun or adjective.

So:

• быть внимательным = to be attentive
• быть готовым = to be ready
• быть осторожным = to be careful

That is why внимательный changes to внимательным.

A useful pattern to remember is:

• должен быть + instrumental

So:

• Он должен быть сильным.
• Она должна быть спокойной.

Both are possible, but they are slightly different in style.

1. должен быть особенно внимательным

   • very natural
   • uses быть + instrumental adjective

2. должен быть особенно внимателен

   • also correct
   • uses the short adjective внимателен
   • often sounds a bit more formal or bookish

In everyday Russian, быть внимательным is extremely common.

Yes, судья ends in -я, but it is a masculine noun when referring to a male referee/judge, and it follows a special pattern.

That is why the verb is:

• судья назначит = the referee will award

not something feminine like назначит—in the future singular, the form is actually the same for both genders, but elsewhere you can see the agreement:

• этот судья = this referee
• строгий судья = a strict referee

So the noun looks feminine but is grammatically often masculine in usage, depending on the person referred to.

In football/soccer Russian, судья is the normal everyday word for the referee.

• судья = referee / official / judge
• рефери also exists, but is less standard in this context and may sound borrowed or sport-specific in a different way

So in this sentence, судья is the most natural choice.

Because особенно modifies the adjective внимательным:

• особенно внимательным = especially attentive

This is the most natural word order.

You could move words around for emphasis, but the neutral version is:

• вратарь должен быть особенно внимательным

Russian word order is flexible, but this order sounds normal and clear.

Yes, but вратарь is the standard native Russian word.

• вратарь = goalkeeper
• голкипер = goalkeeper, borrowed from English

Голкипер is understood and used, especially in sports talk, but вратарь is more neutral and standard in general Russian.

It can work as both, depending on context.

Most naturally, it means a future possible situation:

• If the referee awards a penalty, the goalkeeper must be especially attentive.

But it can also sound like a general rule about what should happen in that situation.

Russian often uses this structure for both:

• a specific future possibility
• a general instruction or principle

So the sentence is not limited to just one concrete match unless the context makes that clear.