Bacon butties are off the menu for 70-year-old Tony Williams, who will go head-to-head with his daughter in this year's Harbour Crossing swim.
Mr Williams, visiting from Britain, is taking part in tomorrow's event, which is raising money for research into children's diabetes.
His daughter, Auckland nurse Helen Greenaway, is also swimming and hopes to beat her father at what is very much his sport, she said.
"Swimming is and has always been his thing and so I'm hoping I just come in at a respectable time."
And she is making sure her father's secret weapon - a bacon sandwich - will be nowhere to be seen tomorrow morning.