Seeded no.1, Nole got to this semifinal without convincing. It appears as Djokovic is struggling with his fitness and he has already dropped 2 sets against Denis Shapovalov and Daniil Medvedev after playing not that well. The world no.1 made it thanks to his highly efficient tennis and mental strength. Djokovic had a free (and important) free pass in the quarters after Nishikori had to withdraw because of a leg injury while he was 1-6 1-4 down.
Ranked no.31, Lucas was under the radar in Melbourne for the most part of the tournament. Eventually, he made it to the semifinals after winning 4 tough matches (see the results below).
Novak and Lucas have never played each other so far. The world no.1 is the clear favorite to reach the final.