The world record holder won with a final jump of 14.81 metres, the best in the world this year and 4cm ahead of her main rival, the world outdoor champion, Sarka Kasparkova, who beat her on countback in Birmingham a week ago.
Hansen's first three efforts were no-jumps, while her fourth reached only 13.89m. Worse followed when she lost her stride pattern and ran through on the fifth. Her final effort, though, was near-perfect, the third-longest jump of her career.
Haile Gebrselassie and Maria Mutola failed in their world-record attempts at Lievin. Gebrselassie had to settle for 7min 31.25sec in the 3,000m, more than six seconds outside Daniel Komen's record of 7:24.90. In the 800m, Mutola finished in 1:57.06 - the fastest time in the world this season but outside world-record time.
In Australia, Linford Christie underestimated his opposition and paid the price by failing to reach the Botany Bay Gift final in Sydney.
Christie, who won the event in 1997, was handicapped off one metre for the 120m race, but finished only third in his heat and did not qualify for the final. He had to be satisfied with victory in the Australian men's 100 yards championship in 9.22sec.