Hijikata taking the match 6-3, 6-3, 4-6, 6-3 in 3 hours and 10 minutes.
The Australian had reached the second round at the Australian Open earlier this year and in his only other Grand Slams singles lost first round at the US Open in 2022.
Hijikata has of course tasted Grand Slam success on the doubles court when he won the Australian Open with Jason Kubler to start the year with a bang.
In the opening set Hijikata needed just on set point to wrap up the set when Zhang hit wide at 40-15. He had broken in the 8th to then serve out the set.
In the second set Hijikata broke in the 7th game to go up 4-3 before holding and then breaking again to claim the set.
Both players were broken in the third set with Zhang breaking in the first game before going out to a 3-1 lead, only to see the set at 3-3. The Chinese player then broke in the ninth game to serve for the set at 5-4.
That 10th game was a real battle with Hijikata have several break back opportunities before Zhang closed it out to stay in the match.
In the fourth set players traded breaks early before the Australian consolidated another break to lead 5-2. Zhang would hold to force Hijikata to serve for the match at 5-3.
After going down 0-30 it was Hijikata that won the next four points, including an Ace on match point to seal his biggest ever victory.
Hijikata has now lept into the top-100 on the live rankings and sits at no. 80.
The Australian fired down 13 Aces to 10, he had 55 winners to 36 and had 36 unforced errors to 47 from Zhang.
Next up is world no. 10 Frances Tiafoe, a semifinalist in 2022.