Step 1: Note what is being asked.
The question wants the winner of the men's singles title at the Australian Open 2026, the first Grand Slam of the year.
Step 2: Eliminate the retired players.
Roger Federer and Rafael Nadal have already retired from professional tennis, so neither could have won this title.
Step 3: Decide between the two active contenders.
Between Djokovic and Alcaraz, it was the younger Carlos Alcaraz who lifted the 2026 Australian Open men's singles trophy.
\[ \boxed{\text{Carlos Alcaraz}} \]