Verco was the first to reach the 35-year-old woman on his board when she was attacked at Coogee Beach.
"I saw the shark come up, and the sheer size was a shock," he told The Sunday Telegraph.
"The shark pulled her down, and I thought, 'What do I do now?'"
But he managed to grab her arm and pull her to the shore.
The woman was flown to hospital in critical condition. She was out swimming with friends when the attack occurred.
It is very unusual for such a great white shark to attack in Sydney, but fatal shark attacks occur on average once a year in Australia.
