Learn Hardcore Croatian: U zadnjoj sekundi utakmice postigli smo gol. - In the last second of the match we scored a goal.

The preposition u (meaning in/at here) normally takes the locative case when it expresses location in time or space (no movement into).
Sekunda (second) → locative singular sekundi.
Zadnji (last) is an adjective, and it must agree with sekundi in gender, number, and case, so it becomes zadnjoj (feminine, singular, locative).

Why is utakmice used here, and what case is it?

Utakmice is the genitive singular of utakmica (match, game).

The phrase zadnja sekunda utakmice literally means the last second of the match. In Croatian, when you say X of Y, Y is usually in the genitive:

sekunda (čega?) utakmice → the second (of what?) of the match → genitive utakmice.

Why is it u zadnjoj sekundi, not na zadnjoj sekundi?

With time expressions, u + locative is the standard way to say in/at a specific moment:

u zadnjoj sekundi = in the last second
u tri sata = at three o’clock

Na is used with some time expressions (na Božić = at Christmas), but not with sekunda. So na zadnjoj sekundi sounds wrong; you need u zadnjoj sekundi.

What tense is postigli smo in, and how does it compare to English?

Postigli smo is in the perfect tense (perfekt) of postići (to score, to achieve).

It’s formed with an auxiliary of biti (to be) in the present (smo) + past participle (postigli).
Functionally, Croatian perfect covers both English simple past and present perfect, so postigli smo gol can correspond to we scored a goal or we have scored a goal, depending on context.
In narratives about finished events (like a match), you normally translate it as simple past: we scored a goal.

What exactly do postigli and smo each mean?

Postigli is the past active participle (masculine plural) of postići. It carries the main lexical meaning: scored / achieved.
Smo is the 1st person plural form of the verb biti (to be) used as an auxiliary in the perfect tense. It tells you the person and number: we.

So postigli smo literally is we have scored, but in normal English: we scored.

Could you also say postigli smo gol as smo postigli gol or smo gol postigli?

No. The auxiliary smo is a clitic and cannot stand at the very beginning or in a random position. It must come early in the clause, usually right after the first stressed word or phrase.

Correct possibilities include, for example:

Postigli smo gol.
U zadnjoj sekundi utakmice smo postigli gol. (auxiliary after the first phrase)

But forms like *Smo postigli gol or *Smo gol postigli are ungrammatical in standard Croatian.

Is U zadnjoj sekundi utakmice postigli smo gol the only possible word order? Can it be rearranged?

The meaning stays the same, and several word orders are possible, with small differences in emphasis. For example:

U zadnjoj sekundi utakmice smo postigli gol. (slightly more neutral, auxiliary in the usual clitic position)
Gol smo postigli u zadnjoj sekundi utakmice. (emphasis on gol)
Postigli smo gol u zadnjoj sekundi utakmice. (when we scored comes later)

All are grammatical; choice depends mainly on what the speaker wants to emphasize and on style.

Why does zadnjoj end in -oj?

Zadnjoj is an adjective agreeing with sekundi in gender, number, and case.

Sekunda is feminine singular, and here in locative.
The adjective zadnji (last) in feminine singular locative takes the ending -oj → zadnjoj.

So the pattern is:

nominative: zadnja sekunda (last second)
locative: u zadnjoj sekundi (in the last second)

Why is it sekundi and not sekunda or sekunde?

Because of the case required by u in this meaning.

Base form: sekunda (nominative singular)
Locative singular: sekundi

With u expressing in/at a point in time, you use locative, so you must say:

u sekundi
u zadnjoj sekundi

Forms like *u zadnja sekunda or *u zadnjoj sekunde are incorrect here.

What is the difference between gol, pogodak, and poen?

All are related to scoring, but they’re used differently:

Gol: a goal in sports like football (soccer), hockey, handball. Here it’s the natural word: postigli smo gol = we scored a goal.
Pogodak: literally a hit; can mean a goal, a hit, or a successful shot. In sports commentary, pogodak is common in a slightly more formal/neutral style.
Poen: a point in some sports (tennis, basketball, volleyball, etc.), not a goal in football.

So in a football context, gol is the basic everyday choice.

Could you leave out gol and just say U zadnjoj sekundi utakmice postigli smo?

Normally, no. Postići is a transitive verb and needs an object: postići nešto (achieve something, score something).

You can omit gol only if it’s extremely clear from context and you’re speaking informally, almost like saying in English: In the last second of the match, we scored. Even then, people usually still say gol or pogodak.

Are there more colloquial ways to say postigli smo gol?

Yes, speakers often use more informal verbs for score a goal:

Zabili smo gol.
Dali smo gol.

All three (postigli smo gol, zabili smo gol, dali smo gol) mean we scored a goal, but:

Postigli sounds a bit more neutral or formal.
Zabili and dali are very common in everyday speech and sports talk.

How do you pronounce zadnjoj? What is the lj sound?

Zadnjoj is pronounced approximately /zadɲoj/:

dnj is like dn
- a palatal ny sound (similar to Spanish ñ in niño).
The j is like the English y in yes.
lj in Croatian (not in this word, but in general) is a single sound, like the lli in British English million / familiar — a palatalized l.

So zadnjoj is something like zad-nyoy, with the ny and y sounds close together.