In 1985 she retained her two national track titles and began to prove herself in cross country running; Sergent won the first of her seven French cross country titles that year and finished seventeenth overall at the 1985 IAAF World Cross Country Championships. In October, she won on the roads at the 10K Foulées de Suresnes. At the 1986 edition of the competition she won her first international medals in the long race, taking bronze medals in the individual and team events. Her continental track debut for France came at the 1986 European Athletics Championships in Stuttgart and although she was eliminated in the heats of the 1500 m, she managed eighth in the women's 3000 m final.