Learn Spanish (Latin America): El atleta invencible va a triunfar. - The invincible athlete is going to triumph.

The noun atleta is invariable, meaning the word itself doesn't change to show gender. Instead, the article does the work. We use el atleta for a male athlete and la atleta for a female athlete. Words ending in -eta and -ista (like deportista) commonly follow this pattern.

Would the adjective invencible change if we were talking about a female athlete?

No, it stays exactly the same. Adjectives that end in -e (like invencible, fuerte, or inteligente) do not change for gender, only for number. So a female athlete would be la atleta invencible.

Since we are learning about reduplicative subjunctives, how would I add "no matter who he competes against" to the beginning of this sentence?

You would use the verb competir (to compete) in the subjunctive twice, wrapped around a relative pronoun like quien (who). The phrase would be: Compita contra quien compita, el atleta invencible va a triunfar.

How would I say "Whatever happens, the invincible athlete is going to triumph" using the grammar from this lesson?