Mi piacerebbe sfidare mio fratello a una gara di corsa, ma lui esita sempre.

Mi piacerebbe is the conditional form of piacere and means I would like.

• Mi piace = I like
• Mi piacerebbe = I would like
• Voglio = I want

So mi piacerebbe sfidare mio fratello... sounds softer and more hypothetical than voglio sfidare mio fratello.... It expresses a wish or desire, not a strong demand.

With piacere, Italian structures things differently from English.

Literally, mi piacerebbe is closer to:

• it would be pleasing to me

So:

• mi = to me
• piacerebbe = would please

That is why Italian uses an indirect object pronoun here. The person who experiences the liking is introduced with mi, ti, gli, ci, etc.

Examples:

• Mi piace la pizza = Pizza is pleasing to me
• Ti piacerebbe venire? = Would you like to come?

Because it depends on mi piacerebbe.

In Italian, after expressions like mi piacerebbe, vorrei, posso, devo, and so on, you often use an infinitive when the subject stays the same.

Here, the subject is still I:

• Mi piacerebbe sfidare... = I would like to challenge...

Compare:

• Mi piacerebbe sfidare mio fratello = I would like to challenge my brother
• Mi piacerebbe che mio fratello partecipasse = I would like my brother to participate

In the second example, the subject changes, so Italian uses che + subjunctive.

With many singular family members, Italian normally does not use the definite article before a possessive.

So you say:

• mio fratello = my brother
• mia sorella = my sister
• mio padre = my father

Not usually:

• il mio fratello

However, there are some exceptions:

• with plural family members: i miei fratelli
• with modified forms like il mio fratello maggiore
• with some less common or affectionate forms depending on style and region

But in a basic sentence like this, mio fratello is exactly what you expect.

Yes. Sfidare means to challenge.

Its pattern here is:

• sfidare qualcuno a qualcosa

So:

• sfidare mio fratello = to challenge my brother
• a una gara di corsa = to a running race

Together:

• sfidare mio fratello a una gara di corsa = to challenge my brother to a race

This is very similar to English challenge someone to something.

The preposition a is used after sfidare qualcuno when you say what the challenge is to.

So:

• sfidare qualcuno a una partita = challenge someone to a match
• sfidare qualcuno a duello = challenge someone to a duel
• sfidare qualcuno a una gara di corsa = challenge someone to a running race

The phrase una gara di corsa literally means a race of running, or more naturally, a running race.

Gara di corsa is a clear, explicit way to say running race.

• gara = competition, race, contest
• di corsa = of running

You may also hear simply una corsa, depending on context, but gara di corsa is more specific and emphasizes that it is a competitive running event.

So:

• una corsa can mean a run or a race
• una gara di corsa clearly means a running competition/race

Yes, it could just be ma esita sempre.

Italian often drops subject pronouns because the verb ending already tells you who the subject is. So:

• ma esita sempre = but he always hesitates

Adding lui gives emphasis or contrast:

• ma lui esita sempre = but he, on the other hand, always hesitates

Here lui helps create a contrast between I would like to challenge him and he always hesitates.

That is a very normal placement for adverbs in Italian.

• lui esita sempre = he always hesitates

Italian adverbs like sempre, spesso, mai, and già often come after the verb, especially in simple tenses.

Examples:

• Arriva sempre tardi = He always arrives late
• Parlo spesso con lei = I often speak with her

Sometimes adverb placement can vary for emphasis, but esita sempre is the most natural neutral order here.

Not exactly.

Esitare means:

• to hesitate
• to be unsure
• to hold back
• to waver before doing something

So lui esita sempre suggests that he does not clearly say yes right away, or he keeps holding back.

It is softer than:

• rifiuta sempre = he always refuses

If he truly says no every time, rifiuta would be stronger and more direct. Esita suggests uncertainty, reluctance, or lack of decisiveness.

Yes, and the meaning would stay very close.

• Mi piacerebbe sfidare mio fratello...
• Vorrei sfidare mio fratello...

Both can mean I would like to challenge my brother...

There is a slight nuance:

• mi piacerebbe can sound a bit more like it would be nice / I’d like that
• vorrei can sound a bit more direct: I would want / I’d like

In many everyday situations, both are natural.

Yes. You could say:

• Mi piacerebbe sfidarlo a una gara di corsa...

Here -lo means him and attaches to the infinitive sfidare:

• sfidare + lo → sfidarlo

This is very common in Italian. Both versions are correct:

• Mi piacerebbe sfidare mio fratello...
• Mi piacerebbe sfidarlo...

The full noun is clearer; the pronoun is more compact.

Yes, it is natural.

A few other natural alternatives are:

• Mi piacerebbe fare una gara di corsa con mio fratello, ma lui esita sempre.
• Vorrei sfidare mio fratello in una corsa, ma lui esita sempre.

These alternatives shift the wording slightly:

• sfidare qualcuno emphasizes the challenge
• fare una gara con qualcuno emphasizes participating in the race together

Your original sentence is perfectly good and sounds natural.