Two-time world champion Daniel Wiffen qualified for the 800m freestyle final after winning his heat.
In the fourth and final heat, Irish swimmer Wiffen placed third in the race, behind the Australian pair of Elijah Winnington and Samuel Short.
The 23-year-old overtook Short at the halfway point and moved ahead of Winnington with 300m to go.
His time of 7:41.53 made him the fastest to qualify for the final, which takes place on Tuesday at 20:00 BST.
Earlier in the pool, Danielle Hill put in a strong swim to finish fourth in her heat and sneak into the semi-finals in 16th place.
In the first event of the day, Ireland’s Ellen Walshe produced an impressive final run to move from seventh to fourth and qualify for the 400m individual medley final in seventh place overall.
![Wiffen fastest in 800m freestyle heats as Hill progresses.page&x1=[urn:bbc:optimo:asset:cv2g8g1xdxyo]&x4=[en](https://whatsnew2day.com/wp-content/uploads/2024/07/Wiffen-fastest-in-800m-freestyle-heats-as-Hill-progresses.page&x1=[urn:bbc:optimo:asset:cv2g8g1xdxyo]&x4=[en-.gif "Wiffen fastest in 800m freestyle heats as Hill progresses 6"){kind=small}