У меня есть шанс купить билет со скидкой, если я куплю его сегодня.

Russian usually expresses possession with the pattern у + [person in genitive] + есть:

• У меня есть шанс – I have a chance (literally: At me there is a chance).
• У него есть билет – He has a ticket.

The verb иметь (to have) exists, but it is:

• Less common in everyday speech.
• Often more formal or abstract: иметь значение (to be significant), иметь право (to have the right).

So У меня есть шанс is the most natural everyday way to say I have a chance.

У is a preposition that normally means by / at / near in a spatial sense. In the possessive construction, though, it is used with a pronoun or noun in the genitive to indicate possession or availability:

• У меня – at me → I have
• У тебя – you have
• У Анны – Anna has

So у меня itself literally means by/at me, but in this pattern it works like I have.

Yes, in some contexts, есть can be omitted:

• У меня есть билет. – neutral: I have a ticket.
• У меня билет. – can sound more like I (do) have a ticket (e.g., correcting someone, emphasizing the fact).

In your sentence, У меня есть шанс купить билет… is the most neutral and standard form.

У меня шанс купить билет… is understandable, but it may sound a bit abrupt or stylistically marked; you would more often hear it in very casual speech or with an emphasis on this particular chance. For learners, keeping есть is safer.

With шанс, Russian typically uses:

1. шанс + infinitive – chance to do something

   • шанс купить билет – a chance to buy a ticket
   • шанс выиграть – a chance to win

2. шанс на + noun – chance for something

   • шанс на успех – a chance of success
   • шанс на победу – a chance of victory

In your sentence, the focus is on the action of buying, so Russian uses шанс купить билет (chance to buy a ticket), not шанс на билет (which would sound like "a chance for a ticket," and is much less natural here).

Both can be translated as chance / possibility, but their nuance differs:

• шанс – a lucky opportunity, something favorable but not guaranteed.

  • У меня есть шанс купить билет со скидкой… – I have a (good) chance to buy a discounted ticket…

• возможность – general possibility / ability / opportunity.

  • У меня есть возможность купить билет со скидкой… – I have the possibility / opportunity to buy a discounted ticket…

So шанс emphasizes that it is a favorable opportunity that might not normally exist, while возможность can be more neutral or practical.

Russian often uses the perfective infinitive when talking about a single, complete action or a result:

• купить – to buy (once, as a completed action)
• покупать – to be buying / to buy regularly / to engage in buying

Шанс купить билет focuses on the fact that you can successfully buy/get the ticket (completed result), so perfective купить is natural.

Шанс покупать билет would sound strange; it would imply a chance to be in the process of buying tickets (repeatedly), which is not what is meant.

In Russian, when you talk about a real future condition, both parts of the sentence usually use future tense, often perfective:

• У меня есть шанс…, если я куплю его сегодня.
  – I have a chance…, if I buy it today.

The logic is:

• The condition (if I buy it today) will be fulfilled in the future.
• Russian marks that future meaning explicitly with куплю (future perfective).

Using present tense here (если я покупаю его сегодня) would sound unnatural or would change the meaning, making it sound like a habitual action, not a specific future one.

Yes, билет is in the accusative singular as the direct object of купить / куплю:

• купить билет – to buy a ticket

For masculine inanimate nouns (like билет), the accusative singular form is identical to the nominative:

• Nominative: билет – a ticket (subject)
• Accusative: билет – a ticket (object)

So you don’t see a change in the ending, but grammatically it is accusative.

Со скидкой literally means with a discount. In English we usually say at a discount or with a discount applied.

The preposition is с, but it has a variant со which is used:

• Before some consonant clusters to make pronunciation easier.
• Typically before с, ш, ж, з and some groups starting with с.

So we say:

• с работы – from work
• со школы – from school
• со мной – with me
• со скидкой – with a discount

Saying с скидкой is technically possible but sounds awkward; со скидкой is the standard form.

Его here is a third-person singular pronoun in the accusative, meaning it / him. In this sentence it refers back to билет (ticket):

• билет is masculine singular.
• The corresponding unstressed pronoun form in the accusative is его.

Important points:

• его in this unstressed form is the same for masculine and neuter: it can mean him or it, depending on context.
• Here context makes it clear it is it = the ticket.

Yes, Russian allows flexible word order, and all of these are possible:

• если я куплю его сегодня – neutral, standard.
• если я его куплю сегодня – slight emphasis on его (if I buy it today – contrasting this ticket with something else).
• если куплю его сегодня – subject я is omitted; this is natural and colloquial, especially if я is already clear from context.

The overall meaning does not change; only nuances of emphasis and style do.

You could say:

• У меня есть шанс купить билет со скидкой, если я сделаю это сегодня.
• У меня есть шанс купить сегодня билет со скидкой.

But your suggested …если я куплю билет со скидкой сегодня slightly shifts the focus: now it sounds like the act of buying the ticket with a discount today is the condition, rather than today being the condition for getting the discount.

In the original:

• …купить билет со скидкой, если я куплю его сегодня.

the idea is: there is a chance to buy a discounted ticket *if (and only if) I buy it today. The word order makes the *time (today) the key condition for the discount.

Yes, this is grammatically correct:

• У меня есть возможность купить билет со скидкой, если я куплю его сегодня.

The difference in nuance:

• шанс – suggests a favorable opportunity that might be rare or limited; it can sound a bit more "lucky" or conditional.
• возможность – suggests practical possibility or capability (e.g., money, time, circumstances).

So with возможность, the sentence sounds a bit more neutral and practical (I am able / have the opportunity), while with шанс it feels more like I have a shot / a chance, possibly limited in time or probability.