I due avversari si alleano.

The two opponents team up.

Breakdown of I due avversari si alleano.

• due: two
• l'avversario: the opponent
• allearsi: to team up; form an alliance

Questions & Answers about I due avversari si alleano.

Why does the sentence start with i? Does it mean the?

Yes. I is the masculine plural definite article, meaning the.

Here it agrees with avversari, which is masculine plural:

• il avversario is not correct because before most words starting with a vowel-like sound? Wait—here the singular is l’avversario
• plural: gli avversari

So you might expect gli in the plural, but after due, Italian commonly uses:

• i due avversari = the two opponents

This is a very common pattern:

• i due amici
• i tre ragazzi
• le due case

So i here is the article for the whole noun phrase the two opponents.

Why is it i due avversari and not due avversari?

Both are possible, but they mean slightly different things.

• i due avversari = the two opponents
  This refers to two specific opponents already known from context.
• due avversari = two opponents
  This is more indefinite.

So the article i makes the phrase definite.

Why is due placed before avversari?