Tsitsipas stands to move from World No 4 up to World No 2 if he can help Greece to the title by winning his semi-final singles match and again win in the final match.
He is set to face Italy’s No 1 Matteo Berrettini in the final four tie which will put 105 points on the table for the Greek in that match.
Tsitsipas will take himself to within five points of World No 2 Casper Ruud but if a win can help Greece into the final he will have a shot at leapfrogging both Ruud and Rafael Nadal and anchoring the Australian Open draw.
Greece could face either Poland or the United States in the final and as both their No 1s are also ranked in the top ten, there should be 180 rankings points on the line for Tsitsipas.
A singles win in the United Cup final should secure Tsitsipas the World No 2 ranking ahead of the announcement of the Australian Open seeds next week.
World No.1 Carlos Alcaraz has also withdrawn from the Australian Open after suffering a leg injury in training.
The US Open winner took to Twitter on Saturday morning to announce the news.
"When I was at my best in preseason, I picked up an injury through a chance, unnatural movement in training.
This time it's the semimembranosus muscle in my right leg," he said on Twitter.
