Alcaraz had never gone past the Melbourne quarter-finals before this year, but the 22-year-old looks well placed to win the title and become the youngest man to complete the career Grand Slam.
Alcaraz replaced Sinner at the top of the world rankings with his US Open success in September, producing a level over the fortnight that most observers considered the best of his career.
The six-time major champion says his performances so far at Melbourne Park have been “pretty close” to that standard.
The manner in which he destroyed Australian sixth seed Alex de Minaur in the quarter-finals – leaning into his greater explosive power and defter touch – was a brutal illustration of how far ahead Alcaraz and Sinner are.
It was also reminder of the emphasis which Alcaraz has put on improving his concentration during matches.
“Not having up and downs in matches has been one of the main goals for me,” he said.
“I’m just trying to play the same level and having the same concentration point after point after point.”
Zverev has proved an awkward match-up for Alcaraz, with the pair evenly splitting their 12 previous meetings.
The 28-year-old’s giant serve remains his biggest weapon and it has particularly excelled during his wins over Alcaraz.
It has also been key to Zverev’s progress in Melbourne – along with being fully fit – as he looks to reach the final for the second successive year.
Zverev has lost all three of his Grand Slam finals and has often been accused of being too passive in the biggest matches.
“I’ve worked on my aggressive game. I’ve worked on my first shots after the serve, my first forehand after the serve, maybe a bit more serve and volleying,” he said after beating Learner Tien in the quarter-finals.
“If those things work for me, then I think success will come.”