The 29-year-old Sjoestroem touched the wall in 24.77 seconds to deny Zhang, who was 0.28 seconds behind, while Gretchen Walsh of the United States took bronze.
Australia's Cameron McEvoy then won the men's 50m freestyle gold in a superb time of 21.06 seconds, beating silver medallist Jack Alexy of the U.S. by 0.51 seconds.
The absence of 2022 men's 100m butterfly champion Kristof Milak and Olympic gold medallist Caeleb Dressel, who also has the world record, will add a dash of uncertainty to the final later in the evening.
But she can expect a tough test from American Regan Smith, who was second in the semis, and Australia's Olympic and world champion Kaylee McKeown who also holds the world record of 2:03.14 in the event having set that time in March.
The Australian mixed 4x100m freestyle relay team have a shot at lowering their world record of 3:19.38 in the last race after cruising through the heats and going nearly two seconds faster than the United States.
Persons:
Sarah Sjoestroem, Stefan Wermuth FUKUOKA, Swede, China's Zhang Yufei, Zhang, Gretchen Walsh, Australia's Cameron McEvoy, Jack Alexy, Briton Benjamin Proud, Kristof Milak, Caeleb Dressel, Dara Rose, Frenchman Maxime Grousset, Josh Liendo, Peng Xuwei, Regan Smith, Kaylee McKeown, Victory, McKeown, Katie Ledecky, China's Li Bingjie, Erika Hairweather, Shrivathsa Sridhar, Christian Radnedge
Organizations:
Marine Messe Fukuoka, REUTERS, United, Marine Messe Fukuoka Hall, Thomson
Locations:
Fukuoka, Japan, United States, U.S, China, China's, Australian, Bengaluru